As we watch the Holy epic Mahabharata, we see Sadhus, Rishis and even the asuras performing meditation and penance (Tapasya) poses for years as a example standing on one leg with two hands folded (Namaskar) to please Lord Shiva, Lord Brahma so that they will be offered boons from them.
Realistically and ideally, it is really difficult to perform this meditation pose as we are born as human beings.
How these difficult meditation poses were performed by them?