Why can’t you grow 10cm of height each year? Toddlers do it very easily, and they don’t even go to the gym. Maybe you just don’t work out enough? Average 40 year-old man should be about 4 metres tall, otherwise he just gave up.

It just requires turning your rational mind off, immersing yourself in the play/sport and trusting things will work out, something which more rational/analytic people tend to struggle with.