God is the creator of all which is good and therefore,what could we give to God which He hasn't already given to us,aside from the fact that doing good is just what we're suppose to be doing.To expect heaven as a reward for doing good is the same as expecting a reward for not doing bad.The good news is that Christ earned heaven for us by dying on the cross to pay for all our sins,and the only thing one can do to gain access to heaven is to give up on all our doing to earn heaven and to simply believe that His death on the cross already paid for all our past,present and future sins.