Wanna hear a joke? A couple years ago, a client sent me a 14-page document at 11:21pm to be edited by 12am that same night. HAHHAHA.
This was early in my entrepreneur-ing career. I had other projects I needed to work on that night. BUT when you're hustling to make it work in the early stages, turning away work feels just plain stupid. So I finished the edit by some miracle and almost had a heart attack. (Now, of course, I'd tell them "Unfortunately, it's too last minute."). At the time, I was stressed, wondering "Why are clients sending me work so late at night?"
Then I realized that it was my fault. I hadn't TAUGHT them any better. Don't begin with frustration at others (your boss, your peers, your clients, etc.). Take responsibility for asserting your boundaries.
People aren't generally bad or mean. (With the exception, perhaps, of the few shady political figures.) They aren't trying to inconsiderate. They want to avoid hurting you. Give them the benefit of the doubt. They will often simply take all the advantage they can unless someone resists because, well, "why not?" (Later, I imposed a "Rush Fee", a nice win-win. You get to procrastinate your face off. I get paid more.)
We don't assert ourselves because "what if someone gets mad?" or "what if they leave me?" Those worth investing in are invested in your happiness. If they don't care, they are a sacrifice you have to make for self-respect. And trust me, others will respect you when you respect your own time, energy, resources, etc.
Take away? Educate your clients, peers, bosses, friends on your rules of conduct. Some simple steps. 1) Learn what you want and need. 2) Decide on your boundaries and standards. 3) Teach people how to treat you. Proactively (read: "BEFORE things go wrong") explain to them your processes and rules so that everyone is clear on your expectations.
And to teach others, you must first teach yourself. Marketing guru Dan Kennedy says that he regularly checks in on his "rules for self-governance". What's okay and what's not okay for you?
Don't put out fires last minute and deal with problems as they pop up from nowhere. Teach people (respectfully, assertively, clearly, with commitment) and they WILL behave around you.
If NOT, say "please feel free to take some jelly beans on your way out."