All our yoga asanas are in preparation for the physical stillness, the anchored balance and grounded mindful awareness that Padmasana, full lotus sitting posture, affords.
As many westerners struggle to maintain this seat for any length of time, there are many easier meditation postures, such as the ankle lock, perfect posture, the half lotus, propping a meditation cushion under the seat, kneeling posture and even sitting on a chair or stool, feet flat on the floor.
Force used in any asana is counter productive: use the full lotus only when your body is adequately prepared, because you risk permanent knee damage. Your ability to enter into inner stillness depends on obviating all distractions, so finding the right posture for yourself is an important step.
Martin Faulk’s video provides interesting info:
It gives you some background on the lotus flower as a symbol
It explains and demonstrates the difference between doing the lotus properly, and how it can damage your knees
It shows you exactly how to train your body for the lotus (training that can benefit you even if you’re using one of the other postures, by the way!)
It emphasizes the critical preparation of the hip joints
It demonstrates, albeit briefly, the related sitting postures you’re more likely to use as a beginner
There is less likelihood of injury, when the ambient temperature around you and your soft tissues are warm
Adapted from warriorcoach.blog.com by Dr. Symeon Rodger