Before anything else: God loves you and trusts you. He gave you things to take care of because He believes you're capable, and that love never changes when you make a mistake.
Think of a funny thing you do every day without noticing. When you go to sit in a chair, do you test it first? Do you bang on it to see if it'll hold? No, you just sit right down. Why? Because you trust that chair. It held you up yesterday, the day before, and last month.
Now imagine a chair that once broke on you. Next time, you sit down slowly, a little scared. It's not that you got picky, it's that the trust went away and it needs to be rebuilt.
It's just the same with people. When you do what you promised and tell the truth, people can sit on your word without fear. They ask you for help, let you take care of things, tell you their prettiest secrets. Being trustworthy means being that sturdy chair for your family.
And there's a really nice part to this story. Trusting is also a gift we give. When you let your sibling play with your favorite toy, you're telling them: I believe you'll take good care of it. That makes anyone happy.