##Pain and fatigue
Pain and fatigue
This plot element was used perfectly in Stephen King's book Firestarter, where Andy McGee could use the push, which was a hypnotic suggestion that could not be resisted. However, each time he used it, he experienced a splitting pain that took a while to go away. The more he used it, the worse this pain would get until, theoretically, it could even kill him. You don't have to use this exact side-effect, but you can safely base it on this, where use of this superpower causes physical pain over time. Just like someone can throw their back, your magical friend might throw his mind!