One of the most important few ways that you can improve your life (along whatever dimensions are important to you) is to be selective about who you spend time with.
The primary criteria is people who have values you feel connected with, and who you enjoy spending time with. But you should also look at habits, and how they spend their time.
If you want to stop drinking, hang out with sober people. If you want to be thin and in shape, hang out with people who eat well and are active. If you want to be more spiritual, hang out with spiritual people.
"You are the average of the five people you spend the most amount of time with."
"Show me your friends, and I will show you your future."
"He that walketh with wise men shall be wise: but a companion of fools shall be destoyed", Proverbs 13:20, Solomon