Too Aggressive
Sometimes we can just hit things too hard. For example if we want to eat healthier, we get so fired up that we toss everything bad out and buy literally everything perfectly healthy. This can be really tough; your body may be like -hey what happened to the junk food. The same can be said with exercising, if you end up going out of the shoot into a program too fast and hard, your body may really hate you for it.
Sometimes baby steps may work better and for others not. Consider the alternatives before you start anything new. In the end this may help some of you to become much more successful at what you attempt to do.