Like many nerds I'm not good at asserting myself.
When business people demand a feature in an unreasonable amount of time, I work around the clock to try to deliver that feature.
The problem is, this impacts my health, both physical and mental.
What tips have you learned for pushing back against unreasonable demands without offending?
Don't be worried about offending them, as they clearly aren't worried about offending you by making you put in extra hours. If you don't have a formal process in place for change requests (doesn't sound like you do), each time they ask you to add something, provide an estimate as to how much extra work that will be. If they kinda look at you like "so?", then translate that into extra days within business hours.
For ex - Monday at 4 PM they ask you to change something - you tell them that that will take at least 4 hours. If they look at you like "so?", tell them "that means it won't be done until tomorrow afternoon."
The truth is always best, so tell them the truth. Perhaps it would also help you if you came up with a different timeline and proposed it to them so they can see the progress towards the feature on a day by day basis.
Okay so one way is when they give the deadline and the requirements. Ask them to give you the priority as well if possible. This is how we got some of our projects under control at work.
While they were doing that, we would also come up with estimates. Then with the priority listing and the work estimates, we would show them what was in and out to make that deadline.
At this point we could make the business decide if they could live with that until the next release (repeat the process!) or extend the deadline.
There is probably no way to do it without causing some tension. But I found this method is very professional, you earn respect by showing you know what you are doing, and eventually (like at work now) the business even starts to follow the process on their own before they talk to you.
I agree that this is a predicament that plagues many technologists. I've struggled with it myself. I recommend trying the following:
Whenever you are asked for a time estimate, overestimate by 2x. Also, say your estimate with confidence. Q: "How long would it take you to write a simple crawler to pull down some documents from xyz.com?" A: "I should be able to finish an initial version in by the end of tomorrow."
Deliver your results in small pieces, and always under sell what you deliver. "I want to show you a preliminary version so I can get your feedback. Please keep in mind that it's far from done and surely has things that you won't like. Still, I want to show you what I have done so far." The key is to say this even when you think you've hit a home run. Undersell.
Try to avoid mentioning technical issues. Instead, if your boss seems disappointed with your time estimate, mention a business or scheduling experience that resonates with them. I like to say something like "I think I can get that done by the end of the day, but you know how that goes. Maybe I'll encounter some unexpected bump in the road and it'll set me back a day." This often evokes a "yeah..... I know how that is...." Avoid going into details about how you realized that you started off with an clumsy design or you struggled to install some new module.
What I do is just say why I believe something is not reasonable, just give good reasons.
However, if its really affecting your health, to be honest I think you should look to make some changes, even if that means changing jobs IMHO no job is worth your health.
As a former software engineer who is now in management my advice is:
If your superiors are doing even half of their job they will have a schedule. If the request is unreasonable it will show in the schedule.
If they don't listen, if they don't schedule, if they expect you to work around the clock, quit and find a new job. No manager should ask that of their employees except in the most extraordinary of circumstances.
Based on your comments, it looks like the work and the unreasonable demands aren't coming from your boss. In such situations, part of your boss' job is to stand up for you. The problem may be your boss, or it may simply be that your boss doesn't know that the demands are unreasonable. Talk it out with your boss.
We use an issue tracking system (Redmine, for the record), that we track Bug, Feature, and other types of issues relating to a particular project. With it, we add estimates to each issue and track progress daily (even several times a day). That way, management can always have a handle on how long something is going to take, as well as get real-time e-mail updates (if they subscribe to them).
If it's a matter of them being uncomfortable not knowing exactly how long a task or group of tasks will take, something like this will surely help them with that pretty quickly. A good project always has a schedule, and a well-managed project usually meets that schedule. A "do it as fast as you can" attitude for production code is never the right answer.
In a roundabout way, my answer is: push for some sort of project management software to be put in place (if there isn't already). It will hopefully get management and the developers on the same page, and ideally cut down on the stress for all parties. If cost is an issue, there are plenty that are free (like Redmine)
I will try to list out all the breakdown of the task, using use cases. I will include all the sunny path & rainy path (when something goes wrong, what should we do)
Remember, listing down those alternate course (rainy path) is very important, because more than 50% of our time spent on it.
Most of the time, our superior only consider sunny path (take for example, login system, they will think they login system is basically user key in username & password, and they expect you to finish in 5 mins, but they never consider, what if user key in wrong, or do something funny). It our job to let them know the alternate course, and the time it takes.
Negotiation always need mutual understanding.
After giving the realistic estimation, you just try your best to achieve it. I won't suggest you work around the clock, just because you superior has a bad estimation. Just do it at your own pace, which won't affect your health.
Perhaps another alternative is, try advise him to drop certain features. This is one of the techniques used in Agile methodology. Focus on must-have feature first, and try to include the good-to-have features in the next edition.
Summary:
Be assertive, but polite. A smile always helps. Manage your managers.
Give them realistic time estimates and add a little bit of contingency for yourself because we all tend to underestimate things. The budget should then hopefully cover for a development time that is realistic. Don't cut corners on delivery time. If you deliver within your time estimate + contingency you will look good. They will deliver within their time and will also look good.
Your manager will probably add his/her own contingency on top of your estimates again.
Never sacrifice quality even if they demand it. Explain that it hurts everyones reputation when things go wrong. Instead, cut features. Something working well but with fewer features is much better than a fuller featured thing that keeps crashing or doing the wrong thing.
I think it often comes down to that management doesn't understand (or care about) the effort involved. If they don't ask for time estimates and just give you a deadline you should anyway insist on presenting time estimates for the individual features, preferably as granular as possible. Then use that as a fact sheet for your reasoning "you see, I will not be able to finish all of the features to that date, could you please decide which of the features you want to omit and which to add at a later date?" That way you are sharing the responsibility with them, asserting yourself in a discrete manner and they will also maybe feel more part of the process as well.
What tips have you learned for pushing back against unreasonable demands without offending?
During the interview I discuss their expectations (re. number of hours per week, who sets the schedule, etc.) before I accept the contract, and prefer to work with managers who don't find that offensive.