Simply consider that meditation is training for the mind and it strengthens your brain function! You would train your body with exercises for muscular and joint strength which improves ease of mobility and helps eliminate toxins and excess weight. Meditation is exercise for the mind 'muscle' my teacher Mukunda would say. The mind needs exercise as well. Meditating cultivates focus and concentration, reducing excess useless thoughts, beliefs and emotions that clutter the mind, thereby creating clarity and 'peace of mind'. It's a paradox that when you meet what is on your mind you are better able to discern where to spend your energy.
Symptoms of discomfort in the body are messages for you to find balance. Uncomfortable symptoms in the body may appear as sensations of stiffness, cramps, weakness, heaviness, aches and pains, etc. When you exercise, you move the energy and blood which burns up the accumulated stagnant energy and cultivates the opposite feeling sensations. Regular exercise brings about feelings of balance - wellbeing. Symptoms of discomfort in the mind are similar and meditation exercises essentially burns away the energy of stuck thoughts and beliefs, that may make you stiff and inflexible (set in your ways), then leaving you more open and clear to see things as they are NOW and even learning and seeing things in new ways.
Click here for an article from the Kripalu Center appearing in the Huffington Post Blog outlining many of the benefits of meditation.