Doing it while it still feels bad

The practical version of all this: act at the point of discomfort without waiting for the feeling to change. Not recklessly, and not on the largest available version — on something small enough that a poor outcome is survivable, and frequent enough to accumulate into a record.

Nervousness before something that matters does not disappear with experience. Experienced people simply stop treating it as a reason to stop. That is the actual skill, and it is available to anybody, because it does not require the feeling to be any different at all.