As someone who had the opportunities to focus on long course tri from my mid 20s to my mid 40s and am about to turn 60, I can testify that what I really miss now is being able to run as fast as I could when I was young. My 5K pace is now slower than my PR marathon pace and I have trained consistently for the past 40 years. So enjoy the 10Ks and short course tris now!

I certainly understand the thought that going long is the holy grail. I decided that for my 60th birthday I was going to train for a 50 mile trail run in the Alps. I've never run longer than a 50K and that was 30+ years ago on flat roads. Although I'm very excited about that challenge coming up in three months, you know what I end up thinking about on a lot of my runs? How I can't wait to return to training where I don't have to focus so much on the mileage and can try to feel fast again.