So I managed to get in 3 miles on the "dreadmill". As Coach Brian suggested, I didn't worry about speed -- just distance. Although, I guess I always worry a bit about speed, because the slower I go, the more time it will take to cover the target distance. But I got my 3 miles in within about 35 minutes. So I certainly wasn't setting the world on fire, but my hamstring is still getting some work and feeling stronger -- gradually.