I am skeptical many people could manage to exercise to 'excess', a little digging online suggests there isn't much evidence[1] there's a real danger, with the possible exception of some competitive athletes - one example that comes to mind is Graeme Obree[2]
1: https://well.blogs.nytimes.com/2013/07/24/can-you-get-too-mu...
2: https://en.wikipedia.org/wiki/Graeme_Obree#Taking_the_record