Muscle loss results from poor nutrition and disuse. Deprived of regular physical exertion, your bulk dwindles. Christians wish for a life without trials, but the result would be smaller spiritual muscles. So God ensures muscle growth, often through trials.
Feed on the Word of God and insist on growing in the Lord; get out of your church comfort zone and take on new spiritual challenges, projects and goals. Those who dwell in your house go from strength to strength. – Psalm 84:4a, 7a NIV.