Growing up is hard.

I have a hard time being mature and being sincere. When it comes to relationships, I don't handle things the way I should, even though I've repeatedly handled things the immature way. I have a hard time saying "thank you" sincerely. I always do a weird voice or something of that nature and make it awkward. I've tried to be less seemingly sarcastic, and it doesn't work. Maybe my real problem is with gratitude.