back to backs

today was my 2nd run of my Back to Back runs.  this is what makes training for the 50 miler different than for the marathon.  a long run on thursday (yesterday was 8) followed by a shorter long run on  friday (today's 4). my coach said several times "its about time on your feet"  not speed.  this will be a big shift for me since I've been working on increasing my speed for the past year.  it was a great morning for running- 60F overcast and not so humid.  and I felt good!  love that feeling after a run where I feel mellow happy calm- is that the runners high?  I don't feel high more like in a zen happy calm place.  which I like :)