You do need to start. At your age your body is adding muscle as you grow. You still feel good.Maybe I need to start then lol I know very few people who work out it’s never been my thing.
In a couple of years, and it’s only a couple, you will start to lose muscle and grow weaker. You can prevent that through strength training.
A lack of cardiovascular exercise will result in early heart disease and early death. You can prevent that, too, and I would recommend that you start sooner rather than later.