It’s a function of your skeletal muscle system. Most people are underdeveloped because of a sedentary lifestyle, or jobs that keep them sitting all day.

You can try to develop these muscles slowly over time, YouTube has a lot of different strategies.

When you’re in the stadium, be dynamic, change postures, if you can do an Asian style squat on the seat.

At the office, try using a stool instead of a chair, or try standing desk. Try to move up the time that you can be dynamic. Bonus points if you get a balance board. Those are great for building that core muscle strength. But it can be tiring so go slow