I'm very new to exercise. I havent exercised regularly since I became pregnant two years ago. I had started doign some social dancing for about 30 minutes a day last week and now I'm going to the gym to use the treadmill for my main exercise.

My question is how do I know I'm working enough? What should I be feeling?

I find myself stopping my exercise at around 30 minutes. I'm never get breathing heavy but I do breath a bit more then resting obviously. If the heart rate monitor on the machine is accurate I never go over 145 and usually stick to 130ish beats per minute. I spend 5 minutes warm up and 5 minutes cool down and 20 minutes at the target heart rate.

I usually think to myself I don't want to walk to much because I don't want sore feet or ankles at the end of the day. I really need new shoes but I have to wait for payday. I think my tennys are too old and don't have enough support.

Good walking shoes are important, so don't delay when pay day comes.

So, are you doing the "fat burn" selection on the machine? That option will keep you in your zone according to that machine's specifications. (Although, they're all usually calibrated for men... )

I guess it depends on what your goals are. Try mixing it up with some inclines at your current pace and see if that's more of a challenge for you.