Well I can only speak from my own experience here.
And i only have three main criteria I hold above all else.
1. Health before anything else! That means make sure you eat right, train regularly and get enough sleep.
2. You should never worry, about anything! Worrying adds stress and contributes nothing whatsoever.
3. Have goals. Thats all, just know there is something you're aiming for. I hate feeling like I have no direction.
Guess thats about it :)