As a roller skater, dance skater, skateboarder, pretty much good at anything on wheels, I figured this would be a walk in the park. I started with the big ball at 4 psi and it took me about an hour to understand how to balance on it. Things I noticed right away: -- lower center of gravity helps a lot (get low!) -- lower center of gravity means your quads will get burned up quickly -- for those exercising by target heart rate: balancing on this thing alone may be enough to get your heart rate in the zone for some of you As I continue to practice I wonder how this will help me balance doing anything else. The thing about balance is that the method or key to balancing is going to depend on what you're doing. For example, balancing on roller skates while swinging, kicking and spinning is like doing all of those things on roller skates. Balancing on a skateboard is like balancing on a skateboard. Sure, there are some things that might be similar, like ice skates is similar to roller skates, but this balance board is not comparable to anything that I have ever experienced. In other words, learning how to balance on this balance board will teach you one thing: how to balance on this balance board. If you wanted to learn how to balance on this board specifically, or just wanted to learn how to balance on something period, or you wanted a good workout in a standalone place, then go for it. Just don't buy this thinking that it will help you learn how to balance for some other sport/activity. Unfortunately, my ball is already lopsided though, so I'm not really sure how I can continue practicing at this point. As you may guess, it is really important the ball is completely round for this. Also I guess the t-shirt was sent to me but it never arrived :( I was really hoping to sport that t-shirt in some videos on instagram.