Personalized Don't Worry About Whatifs Youth Long Sleeve T-Shirt. "What ifs" only hold you back if you let them. Don't Worry About Whatifs Youth Long Sleeve T-Shirt - White from the book "Jonathan James and the Whatif Monster" by Michelle Nelson-Schmidt. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)