Cells are the basic building blocks of life. You are nothing but cells — every organ, every bit of tissue is made up of cells. The number one thing that will make your cells weak is decreased workload. Making less demands on your body makes cells atrophy and weak. The way to get weak in anything is don't challenge yourself anymore.
The reason people get fragile and their bones get weaker is because they don't challenge anymore. People who are most physical make the biggest demand have the greatest strength—whether it be the muscles, the mind, the human emotion, the spirit.
When you're challenged, you use your courage, and it gets bigger by demand. But when you don't use it, it gets weaker; it's the law of life: If you don't use it, you'll lose it.
Today, I want to challenge you to devote a little time everyday for this entire week doing one thing that challenges you. It doesn't have to be anything major—something small is just fine... I challenge you to experience for yourself how this deliberate intent on your part will positively shift you at the end of the week.