Possible Clues:

• Practice whose name means, literally, 'union'
• Slow-moving exercise
• Stress-relief practice
• Discipline with a triangle pose
• Exercise with a lot of bending
• Activity with asanas
• Exercise that might be done on a mat
• Tao Porchon-Lynch's exercise
• With 41-Down, lotus sitters' cushion
• You often get aches at the start — practising this?