1- Don't sweat the small stuff.
(And remember it is all small stuff --fleeting and temporal.)
“External things are not the problem. It’s your assessment of them.” – Marcus Aurelius
2 - Spend time with friends who make you laugh and feel good about yourself.
(And be that friend to others.)
"Nothing, however, delights the mind as much as a loving and loyal friendship." Seneca
3- Move your body for 30 minutes 4 (or more) times a week.
“First say to yourself what you would be; and then do what you have to do.” – Epictetus
4- Drink lots of water. (That's it. Easy one.)
5- Sleep 7 - 9 hours a night. (I can hear you saying no to this one. But seriously, when you do this it takes half the time to do all the things. Plus you feel like a god!)
6- Eat 7-10 portions of fruit and veggies a day. (3 fruit, the rest veggie, if possible.)
7- Practice gratitude -- take a moment now to thank God, or the universe, or fate, or whatever is bigger than you for the beauties of your life, the world, and your present moment. When you get good at that, thank him/her/it for the hardships too. (That one is an advanced move, but it's life changing!)
"Our life is what our thoughts make it." Marcus Aurelius.