This ranks as one of the top 5 runs of my life. Everything was an intensity of senses.  Started out with a 1 mile warm up. I needed a warm up as the temp was 35. Then I headed to trail that starts out in the park behind my condo.  The trail starts up a large hill with a series (8) of steep switchbacks between .05 and a 10th of a mile each.  I did that twice, usually stopping at each switchback. At the top of the 'hill' was a trail that went along a ridge. The trail up there was relatively flat but full of rocks and roots. On one side was a steep drop off. The views were beautiful. The intensity of running along this ridge at 8/mile pace, knowing if I tripped I would fall 100's of feet down, was amazing to say the least.  After my second trip up the hill, I went the other way on trail, into a deep forest of tall pines. Again I had to focus hard on the rocks and roots to prevent a fall. Then back down the trail, smiling the whole way.