“One pilgrim came to me and said that they’ve read a few books about the Jesus prayer and tried to force themselves to do it, but as a result only ended up having heart pain. So I asked him, ‘Don’t you have any ‘material’ for humility (sins)? Acquire humility, and then you will feel how much you are in need of God’s mercy. Prayer will then come naturally, without having to force yourself.’”

(Metropolitan Tikhon Shevkunov pravoslavie.ru)