At worst, I have lived a decent and fairly good life helping others enjoy their lives as well.
With that being said, I would be free from moral restriction and would find it difficult to consider any act by any person "wrong." If there is no God or afterlife, then you will have a very difficult time explaining to me why I should care about anyone other than myself.
Oh sure, you can then quote scientists, nature-lovers, and philosophers to make me understand ethics and moral responsibility, but at the end of the day, there's no real reason why I should care.
That is my honest opinion. Since you cannot prove that there isn't life after death or that there is no God, then I will go on living my relatively peaceful life helping others and being thankful for the things I have in it [Life].