I'm used to this. It's not possible to sit without blanket on the hard ground, but it is very comfortable for me. The knees came down by enduring practice.
In the beginning i needed some soft stuff under the feet. But now they are used to this position.
Because, if our mothers, who have been kind to us
From beginningless time, are suffering,
What can we do with (just) our own happiness?
From 10th of 37 Bodhisattva Practices