You can't let your ego get in the way of your health. I promise that the fear of looking silly doesn't matter in the bigger scheme of things. That short-term discomfort is a lot easier to get through than the risks that come with long-term inaction, and I guarantee that the first time doing something is always the hardest. The second time will seem nowhere near as daunting, and it just gets easier every time after that.
Honestly, if you're looking hard enough, you'll find an excuse to not do anything. But if you want to be fit and healthy and feel the positive flow-on effects in other parts of your life, then you need to break down those mental barriers that are keeping you stagnant. Embrace a bit of discomfort, park your ego to the side, and work out what's more important - your pride or your health.
And for the record, after a bit of time on the court, I'm getting better at tennis. Hopefully, in the near future, I'll be hitting two shots out of five.