Why do all earbuds hurt?

Every ear bud / AirPods I've tried hurt a lot and give blisters, even the extra small tips in the pro 2's. Even the very smallest ones still hurt, I tried skull candy earbuds because people said they were very small but even those hurt too. Are any truly pain free? I have headphones but I want ear buds so I can comfortably go to the gym and run on the treadmill. All suggestions are appreciated