There is a paradox that we overcoming temptations and trials and doubts is necessary to our growth, but at the same time we aren’t supposed to seek them out.  The reason is that the temptations and trials and doubts we seek out are harder to overcome.

when doubting is mistakenly given positive encouragement it turns-out that there are innumerable doubts, which will then mutually-reinforce, and feed-off each other, so multiplying faster then the capacity to overcome them.

-thus Bruce Charlton.

The pioneers trekking across the plain didn’t need to go jogging to sustain their fitness level.  If the handcart pioneers had tried to put in a good five-mile run doing laps around their camp at the end of each day, they would have croaked.

In the same way, we moderns are already surrounded by doubt.  There is no need to detour to find more.