Lama Ole’s answer:
The cause of self-doubt is rooted in wrong views—that is, in one’s way of thinking. It means you are putting the cart before the horse. You should create distance from the “either-or” attitude and lift what is relative and conditioned to the level of the absolute.
Understand that highest bliss is highest truth and that everybody benefits from all the good that happens everywhere. Try not to feel separate from the totality and to always wish all beings happiness. If you are doing better, then others will also do better. And if you feel good, you can also do more for them.
If the self-doubt is of an intellectual nature, then it’s best to use mantras. Mantras are like an oil film on which the disturbing emotions slip back and forth in all directions and then fall away. Mantras protect your mind from its neuroses, and thus deep experiences and joys can develop. Look at you: you have a face, two arms, two legs, and would like to have happiness like everyone else. This is a completely open game. Try to do whatever possible to be happy, and what is not possible today might be tomorrow.
Those who think they have problems should read an international newspaper every day for one week and confront themselves with what is happening in the world—for example, with what takes place in Africa on a daily basis. Then one’s own difficulties are put into perspective and lose their weight.