The best thing is to deliberately click "not interested" and be really consistent about it. When a fitness or gaming reel shows up, tap the three dots in the top right and select "not interested" - do it multiple times in a row and the algorithm will slowly learn that you don't want to see that stuff. This works better for me than just clicking on other things, because Instagram then understands more clearly what you don't like.
On top of that, you can try clearing your search history. Go to settings, search for "search history" and delete it - that way you basically start over a bit from scratch. Some people also say it helps to deliberately follow accounts that post completely different content. Just follow a few creators with topics that actually interest you, and actively engage with their content - likes, comments, shares. That counts more than random clicks.
Important thing: don't expect it to disappear right away. The algorithm needs time and multiple signals to change its mind. For me it took a couple of weeks until the bubble dissolved. And honestly, sometimes Instagram still recycles old content in between anyway - that's normal and frustrating, but it gets better if you stick with it.