If you don’t want your life to be “messed up,” don’t fool around with those who have messed up theirs.
It is a peculiarity of human relationships that it is virtually impossible for one individual to have a lasting positive influence upon members of a group of negative thinkers. Usually, it works the other way. You cannot maintain a positive, productive attitude if you spend all your time with negative people. Those who have wrecked their own lives (and usually blame their misfortune on others) are not the kind of people who will help you achieve success in your own life. Choose your friends and associates carefully, and refrain from complaints about your job, your company, or any individual. Spend your time with positive, ambitious people who have a plan for their lives. You will find that their optimism is infectious.
Excerpt from Napoleon Hill