Throughout your career, and life in general, there will be times when you feel uncomfortable whilst doing a job or completing a task. Your natural reaction may be to stop doing that task (if you can get away with it) or you may want to avoid doing it all together.
My advice to you is to do it more often. It may sound like strange advice but if you follow it, you should find that it helps you improve and grow as a person.
When it comes to public speaking or even presenting to your colleagues, you may find that you shake with nerves or you are very embarrassed or shy. This feeling doesn't last forever. If you had to do this every week, over time you would get used to it. You would be able to look back after a few months and see how much you have improved.
If you manage to succeed at this, think about how good you will feel. If the thing you dreaded the most is now just part of what you do, you have grown as a person. You are stronger as a result. You will be comfortable doing it, which is the aim of this. Don't let it stop there though, look for the next thing that makes you feel uncomfortable. Make a list and work through that list one by one.