I cannot sprint. I suck at running intervals and doing speed work. I hate it. While I can't sprint for two blocks, I can go out and run 5 miles of hills. Since I am not super competitive and basically run for fun (and so I can eat chocolate), I have always focused on training that makes me happy. So, I do longer runs, do hill training, and cross-train. Since I will never be in the Olympics (I think my age alone prohibits that), I don't drive myself crazy for not doing any speed work. I'm not trying to get faster, I'm trying to have fun and maintain my current speed and distance.
Interestingly enough, I have been thinking about this lately as friends have been talking about their interval training and speed work. I think I discovered today why I suck at sprinting! I came across this great article that talks about the human genome and how there is a slight variation in one gene for athletes who are endurance athletes. Basically, the article says that the NRF2 gene occurs more in endurance athletes than in sprinters when looking at competitive track and field athletes. This gene produces new mitochondria which creates energy and also reduces inflammation during exercise. I'm no scientist, but this has to explain my lack of speediness. I clearly don't have the right genes to be fast, but I can go for long distances. Phew! This means I am off the hook for training I didn't even want to do and I will not feel bad when someone running only a mile passes me while at mile 6 in my run! :)
For the full article and more information on this study (which is very cool), see: http://www.sciencedaily.com/releases/2010/02/100218173319.htm.