Hey guys - I am 53 and have been running full barefoot now for 3 months and absolutely love it. I'm a little frustrated though at the time it takes to toughen the feet up. I'm running a consistent 3 miles per outing primarily on smooth concrete with no problem. I tried this week though to run on a fine gravel trail and felt like a preemo rookie tender foot. Maybe it's my age? Anyway, how long should I expect to be able to handle rougher terrains? Am I just too impatient?