What I've learned

1. Physics should be fun, like a video game. When I started doing physics, I thought it was a religious calling and that physics was all about doing important things. Looking back, I realize that I invented the idea of a religious calling because I was afraid of my parents disapproving of me doing physics. I went to an elite college where the professors were all super-competitive and serious about science. My motivation for doing physics was horribly warped. A friend of mine told me that when she was excited about research, she would work enthusiastically all night. She said, "It's like playing a video game."
   
2. Collaborate with a good friend. Science is so much more fun if you can hang out with your friends and do research at the same time! By friend, I mean someone of your level, not your advisor. When I came to grad school, I wasn't used to working with people my age. I had only worked with professors and senior postdocs. Relationships with senior people tend to be very formal. If you want to grow as a scientist, you need to have some freewheeling discussions where anything goes and no one feels embarrassed about anything.
   
3. If you can, find a friend of similar cultural background and gender. This is extremely important if you are a minority. Your cultural majority friends may be the most well-meaning people in the world, but they can't see your whole perspective, only a part of it. It took me a long time to learn this, because I had a very strong ideal that everyone should be culturally neutral, gender neutral, and age neutral. I used to look down on the "women in science" meetings because I thought "these women are bunch of wimps, can't they toughen up?" (The other reason I disliked "women in science" meetings was because the majority of the women were of a different culture from me. So I was a minority within a minority.) The unfortunate reality of the world is that it is much easier for women to be close friends with other women. Similarly, it is much easier for people of the same cultural background to be friends. I was on a hockey team where no matter how much I tried, I never belonged. My teammates were women, but we didn't have anything else in common: different age, different education, different cultural background. Sometimes, a good commonality to bond over is simply sharing the experience of being a minority.
   
4. Don't work through deep depression. It's true that when something bad happens, you should keep going to work and keeping up the routine. But don't do this for deep depression. It's the equivalent of trying to run a 10K race on a broken leg. You only make things worse. Not only do you fail to accomplish anything, you will end up destroying your confidence.
   
5. When you are in trouble, make sure you talk to people who can *actually* help you. These seems kind of obvious, but when you are in a panic, you usually go to whoever you feel most comfortable with. That person may not be someone who can actually help you. If you are having problems in the workplace, you need to talk to people at your current workplace, not your old workplace. If you are having problems with family, you need to talk to people who know your family well or have the same cultural background as your family.
   
6. If you are have a multi-cultural heritage and/or unconventional upbringing, life is even more confusing. My nationality and ethnic background are very different. This is a classic American problem. In addition, I have a gender related problem (hard to explain). My mom was not a good role model for me, so I adopted my dad as a role model and tried to imitate him. I feel uncomfortable around conventional women, but I don't quite fit in with the boys either.
   
7. Lay down your burdens. Bad things happen to everyone, but we have to let go of the past and forgive people. I think I always knew this lesson pretty well, but I mention it for completeness.
   

[Additional note: One of my friends said my post made me sound biased towards certain types of people. I don't want to make it sound like I can only be friends with women or Asians. If I see a Hispanic male walking down the street, I don't think to myself, "Well! There is no way I can be friends with that guy." I strive to be gender-blind, race-blind, orientation-blind, age-neutral, etc. I simply notice that in hindsight, among the friends I gravitate towards most, we seem to have some strong common connection. It's almost possible that I went through a phase where I found it hard to fit in and decided out of bitterness to construct a theory to explain my troubles.]