The more you run from your fears, the bigger they get. The more you embrace them, the more you find they tend to disappear.
If presenting in front of people scares the hell out of you, volunteer to do it more, or put yourself in a position to do it more often. If a senior boss intimidates you, make a point of bumping into them more often so you can speak to them more.
It is only by doing that we improve our performance in areas where we are weak or fearful.
No great progress was ever made in the comfort zone.