Serious yogis will sometimes meditate deeply for hours, so for them preparing that meditation seat with asana is even more important. However, as you probably have already experienced, even short meditations can bring pain in the back, knees, or some other part of the body. It is possible to just start with short meditations and slowly work yourself up to longer meditations, thus strengthening the musculature in that way, but it is a less effective and more uncomfortable than preparing for meditation with a regular practice of yoga asanas. This is a good time to consider adding a yoga practice to your schedule. Meditation is a mental exercise that reduces stress in the mind and correspondingly in the body.
Yoga asana is a physical exercise program that reduces stress in the body and thus in the mind.
The optimum program is to work on stress reduction from both sides, as your results will be greater than the sum total of each practice because they strengthen one another. This would be a good time to review the other limbs of traditional Ashtanga, or Raja Yoga. After asana, the third limb, comes pranayama. As you know, pranayama is breathing exercises, as they are our single best handle on our mind. Then comes Pratyahara, withdrawing the mind from sense objects.