You never know what is going through someone else's head. Be kind.
Exercise has a positive effect on my mood. So go do something. Now.*
Small wins compounded lead to huge results.
It's easy to get consumed in looking at other peoples' success. That won't help me. Focus on myself.
Strive to improve 1% everyday (I recommend reading this).
You can always improve, learn more and do better. Ego inhibits this so leave it at the door.
Whether you think you can, or think you can't, you're right.
*Even if it's 5 pushups or a couple of pullups, do something.