As an athlete the goal is to get in the best possible shape. Many athletes will cross train by running, biking, swimming, and other training programs to stay fit.
I am sure the apostle Paul knew what it took to be in shape. He did not just hop into his Hummer and take off on his missionary journeys. He hoofed it to get from place to place. I don’t doubt that he was in pretty good condition. He wrote often about athletes and staying fit, understanding the need for spiritual fitness. Paul knew in order to battle his spiritual opponents, he had to be in the best spiritual shape possible. He studied God’s Word, prayed without ceasing, and fellowshipped with countless believers. He knew spiritual fitness would draw him closer to his heavenly goal.