Does that sound familiar? I've heard it numerous times over the years. I don't doubt that these folks are being truthful; they're not just making up lame excuses. It should come as no surprise that they get hurt. You can't go from doing nothing straight to high intensity training! You've got to start slow and train smart.
"I felt totally fine before I started training; exercising only messed me up," they might lament. Truth be told the only reason that they felt fine was because they were doing nothing! The first time that they have to do something as extreme as take an extra large step to avoid stepping on the cat's tail — BAM, they're injured! My theory is that sedentary adults have all sorts of incubating injuries just waiting for the first time that any kind of musculoskeletal stress is applied.
So, how can it be avoided? How can this poor person who can't even get to first base on any kind of workout program actually find fitness success? It's about going slow, steady, and taking the small steps. Learn how to tackle the tasks here.