Even seasoned martial artists need to work on their mental strength to break through the barrier cleanly.
When you feel your heart racing and your palms getting clammy the trick to to center yourself.
Take some deep slow breaths. And take your time.
Stand and face the board and look at it as a hudle.
Now imagine your perfect kick or strike powering through the board.
And see the wood lying in pieces on the dojang floor.