Stop giving everything they want. Leave something for yourself.
Start saying no. Eventually, they will stop taking you for granted.
You don't have to please everyone. Just don't.
If you want to say the truth even if it hurts others, say it. It's the right thing to do.
Frown. Get angry. Be a bitch. You don't have to be nice all the time. You have your bad days too.
If you're frustrated, scream. Ignore everyone.
Don't like someone? Then, don't talk to them.
Stop making everything your fault. You did your best. If something failed, then do better next time. You know you can do it.
Try lifting yourself up. You don't have to put yourself down just because you don't know how to be proud of yourself. Be cocky. Be confident.
Smile if you achieved something. Brag about it. You know you worked hard for it.
Sometimes, it's okay to let out your frustrations. Don't bottle it up.
It's good being nice. Fulfilling, even. But you have to know that you have your limits.
Be nice. But don't be an idiot.