参考答案

正确答案：give it regular workouts
give it regular workouts 解析：题干中的Your ability to control your mind and body与该句中的it(指代首句提到的self-control“muscle”)对应，become stronger与grow stronger and stronger对应，use it properly与putting it to good use对应。空后的and表明，本空所填成分与use it properly并列且有共同的主语you，故文中时间状语从句中you后的give it regular workouts即为本题答案。