The spirit is willing but the body is weak. (Matthew 26:41)
That verse struck me while in the middle of prayer. I just realized that our body is our limit. The Spirit may want us to do something but if our body is not fit to do it, we may just end up frustrated in not being able to do it or at least have no strength to do it.
The context of the verse may imply that the flesh resists any spiritual activity, but this verse may also imply that though the spirit yearns to follow God, yet if the body is physically weak or sick, we may not be able to fulfill His will at all.
It is very important to be healthy and strong. Even youths grow tired and weary but those who hope in the Lord will renew their strength (Isaiah 40:30-31). I believe it is a supernatural strength but it could also be a strength that comes from a life that is lived right. Those who live right, do right, think right, sleep right, eat right and definitely exercises right.
The young Israelites in Babylon were found to be more healthy because they only eat vegetables than those other young men who fared at the king’s sumptuous table probably composed of high carbohydrate, fatty and oily foods. (Daniel 1:11-16)
Even John was happy that everything is going well with the believers both in spirit and in health (3 John 2). Stay fit and healthy so you can live a stronger and longer life and be able to love and serve God with all your heart, soul, mind and strength! (Mark 12:30)