Gary Dudney recently offered some ideas for older and/or slower runners like me, including the gem:
Dave Olney, veteran of many 100-mile runs, tells of how he changed his outlook on participating in long races when he discovered his strong walking pace would get him to the finish. "Instead of feeling like I had to run, run, run and feeling guilty every time I was reduced to a walk, I assumed an almost Taoist state of calm. I realized that I could walk the hundred miles at a good clip, and whenever I felt like running I could put a little extra time in the bank."
Wisdom that I need to learn!
(from the article "Run for Your Life!", subtitled "Aging is Not the Enemy of the Runner as Long as the Running Can Be Kept Fresh", in the November/December 2004 issue of Marathon & Beyond magazine; see also LightMind (22 Aug 2002), SlowerRunnersGuide (30 Oct 2002), DeadBrainCellTheory (6 Apr 2004), Eric Clifton (1 Oct 2004), ...)