Scared of re-injury after trying to build strength

This morning, I was on a call with a recovering runner who signed up for a series of coaching calls to get back to running after a long-standing injury. 
 
This is an elite athlete who had multiple setbacks, and encountered difficulty getting over the hump a number of times. 
 
If you're going to get back your fitness, and if you're going to get back to training as fast as possible, you're going to have to endure some discomfort, some risk, and frankly, a little bit of anxiety every time you bump up against your limits. But that is part of the recovery process.
 
Are you scared of re-injury after trying to build strength when you've had a running injury? 
 
Well, that's what we're talking about today on the Doc On The Run Podcast.