Don't give yourself a hard time about what you can't control - other peoples circumstances; their feelings, their reactions.
Be selfish on occasion and say no - especially if saying yes would effect your life negatively (overwork, stress, lack of sleep).
Let go of past hurts. The person who wounded you is not affected by your pain, so it only holds you back.
Take time to breathe and smell the air (except if you're in a polluted city, then find some nice flowers to help with the breathing.)
The world won't stop if you do, so make sure you stop.
Remember what's important.
Remember who you are.
Remember what you value.
Don't compromise unless you both truly gain joy & peace from it. If you let go of your values and ideals to make someone happy you will ultimately become unhappy.
Remember to breathe.
Remember that friends are to be cherished. Share you heart and life with them. Don't take them for granted.
Remember why you do what you do. If you can't remember stop doing it.
Remember to be good to yourself.