Meditation is 100% a mental activity
Meditation is an activity we do with our mind. It's 100% a mental activity. Why? Because during meditation we do not move any part of our body. If you have ever seen a Buddha image or statue, you normally see him sitting with his eyes closed. It's the image representing his enlightenment and also his meditation position. Physically we don't see anything change or move when we meditate. But mentally, something happens.