Pareto principle http://en.wikipedia.org/wiki/Pareto_principle (also known as the 80–20 rule, the law of the vital few, and the principle of factor sparsity) states that, for many events, roughly 80% of the effects come from 20% of the causes
Parkinson's Law http://en.wikipedia.org/wiki/Parkinson%27s_law Parkinson's law is the adage that "work expands so as to fill the time available for its completion".
Figuring it out though can be the difficult part.
In baseball terms, round the bases with singles instead of always swinging for the home run.
Also, don't marry someone that you'll have to give everything you've ever earned to get out of your life.
It's hard to summarize all my life's experiences. I tried very hard to learn from my parent's and other's mistakes. I'm not a failure, but I'm not retirement wealthy either.
Best advice is read a lot of writeups on failed startups more than successful ones (if that's your goal). You learn more by seeing where people could have done better than by studying those that for the most part got lucky (yes they worked hard too, but sometimes timing, connections, location, etc. doesn't work out).
If you're looking toward just being successful in your career, that's a different line of study (how to win friends and influence people, etc.).
If you'd like to have an actual discussion, shoot me your email. I'd meet the criteria for failed startup founder (I'm on #7 or 8 right now, too lazy to go review how many failed I've had :-)
Luckily we basically threw in the towel one day and said it wasn't worth the stress anymore. We learned the importance of Pareto's Principle, Parkinson's Law, and a good nights sleep.
The crazy thing is our grades remained unchanged.
These were great life lessons that we learned that I wouldn't trade for the world.
Although I chose not to pursue medical school, both my buddies are in their first years and they constantly witness similar experiences to the article above and our initial undergraduate experiences, regardless of the schools that their classmates graduated from - MIT included.
Meanwhile my friends are doing very well in graduate school and continue to have just as much time as during our undergraduate years.
I hate to say it, but if it wasn't MIT, it probably would have been something else for these kids.
Hard Work != Productivity