When I was a young person I struggled with doubt. You might say that I wasn't born with the "gift of faith." Don't get me wrong. I believed what I was taught; it just took constant effort. I served a mission, married in the temple, had kids, went to church, performed my callings, honored my parents, etc. In retrospect I think my efforts were no less sincere than those who felt they knew with certainty.
Mormons say that anyone can gain a testimony through prayer, fasting and study. I did all those things and really never had anything to show for it except almost overwhelming cognitive dissonance. When I eventually lost my faith, I felt a sense of relief. It was like putting down a heavy stone.
You might chalk this up to a moral failing on my part. Like many people, though, I think my behavior improved after I discarded my prior system of belief. I became more generous with others, less judgmental of difference and showed more personal integrity in various areas of my life. (My theory: people tend to behave better when they are under less stress.)
A question I have is this: why does belief come easier for some people than for others? Is it just a character trait like curiosity, assertiveness, extroversion, etc.? If you can get past the official position that prayer works for everyone (it doesn’t), what are you left with? The usual LDS explanation (faithfulness in the pre-mortal existence, being a "choice spirit," etc.) just deflects the question by pushing it back to a hypothetical earlier phase of existence.
This is not an easy question.