A review of Fit For Eternal Life, by Kevin Vost, PSY. D., explains some very useful fitness facts, especially for the Christian.
The book states that a little bit of something does more than a whole lot of nothing! Also, there is a time for work and a time for rest. The minimum attendance of Mass each week is once. What is the minimum frequency for strength training? Also, once a week. More could benefit in both cases but as each Mass has different readings, psalms, prayers for specific feasts, etc., so should workouts be varied in content and alternated to prevent overtraining. But remember the good news: all we really need for productive strength training is one weekly session!
As for aerobics, billions of human beings kept themselves lean and fit for ages before the discovery of the aerobics revolution. You can lead a healthy life and be fit by eating sensibly and burning calories through an active lifestyle by: washing and drying dishes, doing laundry, sweeping, grocery shopping, putting away groceries, dusting, window-washing, lawn mowing, washing you car, stair-climbing, gardening, ironing, dancing, etc.
As for the foods we eat, our bodies have become overstock supply warehouses. What do we do? We buy diet books. Then, we make unbalanced and unappetizing food choices that can't be sustained for long. Cabbage soup for breakfast? As for nutritional supplements, Vost believes they do more for their manufacturers' and advertisers' wealth than they'll ever do for your health. Faith helps us rejoice in the fact that we are wondrously made by God and wondrously gifted with the capacity to transform and perfect ourselves.
Charity then sets the goals and standards for the virtue of fitness. The principal act of charity, according to St. Thomas, is to love and out of the love of charity with which we love God, we ought to love our bodies also. As we grow in physical prowess, we must train our bodies as instruments of charitable works. We must display the fortitude to persevere in our training and diet.