Lemme guess. It's a Polar.

I went through the same thing in 2008. I didn't get the heart rate monitor for running; I was running and when I moved to California I decided that some upper-body stuff would be good so I bought an ergometer. It would read a Polar so might as well, right?

What I discovered is that the Polar wanted me in a stupid place between speed-walking and slow jogging, which was intolerable. I could keep at its happy heart rate on the erg for an hour and a half at a time but with all the hills around where I lived, it was a constant frustration of running ten paces, then walking five, then running seven, then walking eight.

What worked for me was running further. In High School I ran like eight miles a day. After my misadventures with the HRM I bumped from 2 to 3.5-4 mi and enjoyed it a lot more.

And a pair of these. Took a minute off my mile times... at least for a couple weeks. Then I think I broke a metatarsal. Then the shoes were so hammered that I can't really use them the way they're supposed to be used without thinking about it way too hard. At least they weren't expensive. Oh wait, yes they were.