Really cute! I love the illustration! I know little boys can wear sleeveless, but could you add short sleeves - I think it will look more refined (and more people will be able to relate to that kind of image)
The top -Fitness 4 Boys - should be made larger - is there a logo that you could put on the top instead of those words?
I don’t love the yellow in the words (stretch, run, jump) - it would look sharper if it is a solid color - you could also maybe add more interest to the words by stretching the word stretch - make run - italic, and jump - have the letters one up one down… not sure if I am being clear enough…
Align the icons with the paragraph of text. The copy is good.