I tweaked my achilles tendon due to over training on a local trail.  I'm taking physical therapy now and making good progress so it will be about two weeks before I get back to trying to run.  I was in the 5th week of C25K and making good progress and got the big head, so switched to a marathon training program which upped my time and distance which backfired on me.  When I start back I plan on starting C25K over from the start. Since trail running is what my ultimate goal is I was thinking about doing the C25K on the trail instead of on the flat levee dirt road I initially started on.  The trail I will be using is not drastic as far as hills or root, rock etc.  It is gently rolling in places, we are relatively flat down here in Mississippi.  I have run several short times on this trail, what got me in trouble was doubling the time and distance I was used to running, which of course caused the overuse injury.  I realize I'm trying to talk myself into it being ok, but would appreciate any opinions.