You have to feel confident. If you don't, then you're going to be hesitant and defensive, and there'll be a lot of things working against you.
My grandfather lived to be late 90s on one side and on the other side, 70s or something. And my father died young, at 63. But he didn't take very good care of himself.
What you put into life is what you get out of it.
I was always respectful of people who were deeply religious because I always felt that if they gave themselves to it, then it had to be important to them. But if you can go through life without it, that's OK, too. It's whatever suits you.