Question about workout intensity

To all:
I'm trying to figure out if my workout is intense enough--and if my workout is keeping me healthy.
My workout goals/objective: 1) to prevent the onset of Type 2 diabetes (I'm about 20 lbs overweight--though I've been heavier and my blood sugar levels were higher years ago); and 2) to achieve the overall benefit of working out about 25-30 minutes a day.
I've started working out 25 minutes a day first thing in the morning. But today when I worked out on the exercise bike, I didn't feel the great post-workout feeling I have in the past (I worked out about 35 minutes today.)
Please tell me what stats are important when working out: pulse rate or whatever else I should be striving for.
Thanks!
--Pete

If all you're doing is a little peddling on a stationary exercise bike I would venture to say that you would benefit from A LOT more intensity in your training. Regardless of what your goals are, you will get there faster if you train a little more like a meathead. What I mean by that is, meatheads go in the gym and they get pumped up and they dominate their workout. Sitting on a stationary bike for 35 min isn't really dominating a workout. Try doing something that is more exciting that you can really get into because without a proper mindset you will never achieve a high level of exercise intensity. Maybe go cycling outside and periodically stop and do push ups and bodyweight squats, buy a kettlebell and do viking warrior training or sign up at a gym and start a lifting program that you do in conjunction with your cardio.

As far as what heartrate to aim for, I usually just go for the my-hands-are-shaking-and-I-feel-like-I'm-drowning approach. IMO, if you have to look at a screen to tell you if your heart rate is high enough, it isn't high enough.

I rode my bike on a trainer indoors this winter. It is what you make it. Put on some good music and put in the effort, you can get a good burn! Before I got a heart rate monitor, I went by the old "you can talk but not sing" as far as when I was working hard enough. Good luck!

Intensity isn't determined by what you do or how long you do it. It's how hard you're going after whatever it is you're doing. That said, you could probably do a bit better.