For example: being punched in the face and swimming in open waters.
As for how, to my knowledge there’s only one way to overcome any fear and that’s exposure to the fearful stimulus. e.g. One loses (at least greatly reduces) fear of being hit by sparring.
The maples have grown old; Orchards have begun to wither. The reds and greens have faded. Climbing the heights, I Feel the chill of late Autumn. A ceaseless pounding sound Drowns out the setting sun. Remembered sorrows flock To mind, making new sorrows. We are separated By a thousand miles; From our two distant places We can't even meet in dreams. The rain stops, and the sky clears; One can see the twelve green peaks. Speechless, who could understand My angst, as I stand cliffside. I can write of my grief, but Will the clouds bring a reply?
Some say the world will end in fire, Some say in ice. From what I've tasted of desire I hold with those who favor fire. But if it had to perish twice, I think I know enough of hate To say that for destruction ice Is also great And would suffice.
A loose shard of thought Flips and twists about in My brain, Poking sensitive tissue, And sending firestorms Riffling through my circuitry. I can't really say I feel each Prickle or pierce, but they Do make me wince, sometimes.