I think all my hints finally got through. My hubby bought me something for my birthday that I've had on my Amazon wish list! A Polar FT1 heart-rate monitor. I have used it for every single workout since. I love having an accurate indicator of how hard I'm working and whether I'm working out in the fat-burning zone or in an anaerobic zone. You input your maximum heart rate and your minimum (I put in my 50% heart-rate number there). Then, it tracks what your average heart rate is for your workout and what your maximum heart rate was for that time, too. I wish it kept track of all your workouts, but I think I have to upgrade to another FT heart-rate monitor for that capability. This one is great for my needs right now, though.
Having this wonderful little gadget has shown me that I was pushing myself far above the fat-burning zone for far too long (both duration of workout time and for years). I notice that when I run, my heart rate always goes higher than when I cycle or swim. I also have noticed that as I work in a 75-85% heart rate for most of my run, I've gotten not only faster, but my heart has gotten stronger. For example, whereas my heart rate was easily near 90% for much of my hill runs when I first got the heart-rate monitor, it's now well within 85% of my maximum heart rate and it's only been a month!
For those of you who don't pay attention to your heart rate while working out and wonder why you're plateauing, this device will change the way you workout and it will bring you results. Heart-rate monitors start around $60 and they're well worth the investment if you're serious about getting in shape or increasing your fitness level.
Not sure about what your heart rate should be for your age? Here's a helpful chart.
What are the workout gadgets you can't live without?