A lot of the time I don't think I deserve things so I stop letting myself have them. Don't do that, there are so many things in life you can never earn or deserve but that doesn't meant you have to stop receiving them. The biggest one is God's love, you will never in a million lifetimes be able to earn God's love and forgiveness and you will never be worthy of Him. He loves you anyways, God knows how messed up you are and yet He still loves you unconditionally. Just because you don't deserve someone's friendship or you don't deserve to be on the sports team doesn't mean you should remove yourself. Enjoy it and try to work to be better than you were but know sometimes there are standards you can never live up to. Work towards those standards but don't get too frustrated with yourself when you fail. You can never be worthy of God and all that He has given you. He has given you your life, all your possessions, your circumstances, and your friends even though we constantly mess up. Our goal shouldn't be to deserve God's love it should be to grow closer to Him.