I've been exercising using the treadmill and the stationary bike. I've done the Couch to 5k program for 3 weeks, but I didn't do the program this week - just walking at 4mph. I've been wondering what I should try to feel the burn!! I can't remember the last time that I've been sore after exercising, and I want that! I want to feel like I've worked my body. Even after running on the treadmill for Couch to 5k (my first time running EVER), I didn't feel it the day after. What new things should I try? I occasionally take my heart rate and it's where I should be, but I don't feel it.

Any suggestions??

hah hah try tae bo and the burn will kill you ;-)

Mmmmh, take on some weight-lifting instead of the treadmill. I guarantee you that you'll feel veeeeery sore after this

Okay, seriously about the treadmill/bike stuff, I'm not sure. I've never been sore on these either, and upping the resistance/incline by much is a tricky way of "working" more (or at least, I suspect that causing your heart to race too fast for the duration of a regular cardio workout would be a bad, bad thing).

Kery is right -- Once you get past the initial adjustment period from no activity to activity, you're not going to feel sore after a cardio workout. Cardio can help build muscle stamina, but that's not going to make you sore afterwards. If you are moving in a novel way, doing an activity you've never done before or not in a long time, you can feel sore the next day, but again once you get past the adjustment period you're not going to be sore any more. Strength training, on the other hand, overloads the muscles in terms of their workload abilities, and the aftermath of THAT type of training can be soreness.

By the way, "the burn" is not the same thing as post-workout soreness. When people say they "feel the burn" it is due to lactic acid building up in the muscle during a repetitive activity.