So… if you want to be happy and live longer then become a Christian so you can go to church and stay married.
Of course, you have to assume that the stats, polls, or surveys are all accurate. They may be. Or they may not be. But even more to the point, becoming a Christian is not about what makes you happy or helps you live longer. It is not even about helping your marriage. Being a Christian is about restoring your relationship with God. That is why Jesus came to earth. He came to be a way back to God. Being a Christian is about how much God loves you. It is about God and Jesus wanting you to live in relationship with them forever.
As a Christian, you may not always be healthy. Christians get sick because we live in a fallen and corrupted world. Jesus even said we would have trouble in this world. He also said he had overcome this world. You may not live a long time on this earth even if you are a Christian. If you are a Christian, this world is not your real home. Realize the life that God invites you into is for eternity, and not just for the little while you are here.