The body can’t feed off of anticipation but the mind can. And that’s what gives it the strength to keep going. So faith is an important way of nourishing the mind.

"You’re not here just stuck in a bad situation where there’s nothing you can do about it. Even though there may be limitations on what you can do, you always have the opportunity to do the skillful thing, say the skillful thing, think something skillful. And that will be your food down the line.

Even though the refreshment and the nourishment and the rapture may not be coming immediately, the simple fact that you’re convinced that there will be something good coming down the line gives you energy right there.

Because the mind is not like the body. The body can’t feed off of anticipation but the mind can. And that’s what gives it the strength to keep going. So conviction is an important way of nourishing the mind."

~ Thanissaro Bhikkhu "Feeding Off the Future"