Forget about chasing high salaries. It's just not worth it. As long as you're earning enough to comfortably support yourself and those that depend on you, that's enough. Health and happiness come first.
Don't tolerate bullshit from anyone, especially yourself. Set high standards and meet them; the satisfaction of a job well done is a reward in itself. Take pride in what you do and approach your work as a vocation, not a job.
If you find yourself in a toxic environment, leave. After seeing my father suffer from the stress of one in my formative years, I made it a policy from the start of my career to avoid large corporate environments at all costs. Maybe some of the are good, but I don't want to take the risk.
Become an expert in something. Make a substantial original contribution to knowledge in your field that advances the state of the art. This is actually an explicit requirement if you want to get a PhD, which I've found to be a valuable way of opening up fulfilling career opportunities that would otherwise not be available to me. Caveat: The process of getting there won't necessarily be a pleasant one, and some parts of academia can be just as toxic as corporate environments. I was pretty lucky in my experience with this.
Move to a country with a low cost of living, while working remotely for a company in the west. Your income will go a lot further, and you can use that to either support a more comfortable lifestyle or work only part time while still being able to support yourself.
Do something you're passionate about. I know this one is a cliche and lots of people will tell you it's unrealistic, but they're wrong.
Stay away from circumstances that cause you to descend into cynicism. It's very easy to become negative and give up hope when you're in a toxic environment, and if you find yourself in one than you need to escape. There are good companies out there run by people who have a clue and are genuinely nice to work with. Don't settle until you've found one.
Most people usually suggest making your children a priority, and not let your career get in the way of a healthy family life. Generally speaking they're correct. However if you don't already have kids, be aware that when the time comes you might suddenly discover that for medical reasons you are not going to be able to have them. If this happens to you, and you suddenly realise that all you have left is your career, you better be damn sure you've prepared in advance for this so you've got something to fall back on. It softens the blow, a bit.
Find good people to work with. This is probably the single most important thing, from my experience. A good manager and good colleagues are worth their weight in gold. Treat them with respect and loyalty, and they'll do the same for you.
Strive to leave a legacy. We all have a short time on this planet, and there's a lot to be said for leaving the place a little better off than the state you found it in.