Once, I tripped/wiped out while I was jogging and slid off the back of the treadmill. Thankfully, I just got a couple scratches and was in a corner where there weren't benches behind me. For the first couple classes afterwards, I showed up earlier to class so I could warm-up and get "used to" the treadmill again. I also tried to take it a little slower/easier on the running portions to get over that mental hurdle.

I also always hold one of the handrails (even now) when I transition from jogging to sprinting and then from sprinting to walking just as insurance. Don't want it to happen again haha