Guys, stop feeding the trolls.
5k training: How many of you use a heart-rate monitor and plain workouts around them? I really like using mine and think it gives the best feedback about where my body is.
Never bothered. I tend to track my resting heart rate as a better indicator. Low 60's is is my slovenly rate with only occasional excercise. Low 50's is when I have been doing a good job with regular workouts. Mid 40's is when I have been getting my bad-ass training in for something major (bigwall climbing, lots of backpacking, etc). All time low was 43 bpm in my 20's. Currently I have it down to 48 bpm.
In years past when I went to the gym and used the excercise bikes or stairmasters with monitors I saw a nice correlation. If I was in the 60's resting I could hit 150 bpm and feel close to maxed out at a very low setting. By time I had my resting down to low 50's it was very hard to get up to get past 140 without the legs maxing out first, and most workouts were thermally limited more than cardio limited (why are gyms so warm even in winter?!). I would use 150 as my target and hold my heart rate there for the entire workout if I could to avoid overdoing it, but to avoid cheating.
These days I hate those machines and just ride my real bike and run. I ride at whatever speed I feel like that day, and run at the same crappy 10 min/mi pace no matter what, just for longer distances. I have gradually gone from have to work up to 3 mile runs to being able to do 4.5 mile runs off the couch after a winter thanks to the steady bike riding.
This summer I went from zero running (well, occasional ultimate Frisbee) to running 6.5 miles in 6 weeks and then doing Hood to Coast which was 6.8, 5.3, and 5.2 mile runs as part of a relay team within just over 24 hours (grand fun). I kept things up and now I have been able to run the 7.5 miles home twice in the last 2 weeks without anything more than tired muscles the next day.