I went for a run this morning before the sun came up. There was a moderately hard frost on the ground and some ice on the sides of the roads. Since I'm not much for the cold, it was chilly. I did a few push-ups and sit-ups afterward and then took a shower. It felt great to exercise again.
As I ate breakfast, I was reading an article by President Uchtdorf. He quoted Harold B. Lee, who said that it is what we do about what we know (about spiritual matters) that helps us to maintain that knowledge.
That is, we learn about spiritual matters through the mind and spirit. The evidence of such matters consists largely of thoughts and feelings, which are ever so easy to forget. If we do not act in such a way that we can continue to receive thoughts and feelings from God through the Holy Spirit, then we will lose sight of the evidence that we once had.
After a moment of reflection, I concluded that God gave us our bodies the way they are for a reason. He gave us bodies that require maintenance: exercise, good nutrition, hygiene, and caution. Learning to care for our bodies teaches us how to care for our spirits. We exercise our spirits by doing the things that we know we should do. We nourish our spirits by studying God's words and by praying. Spiritual hygiene involves careful and honest introspection and frank conversation with God, asking Him to forgive us when we fall short. And we should be careful to avoid wounding our spirits through sin.
As we care for our bodies our spirits, we will find similar results: we will be stronger, healthier, and happier. And God is kind enough to teach us about one by showing us the other.