I can't promise you...

I can't promise you the whole world, but i can try to give you a very happy life. 

I can't promise you I'll never yell but i can try to be patient most of the time.

 I can't promise you I'll never make mistakes but i can try my best to correct my faults.

 I can't promise you that i'll catch you every time you fall but i can try to always be close so i can help you back up.