I was advised to try to do a minimum of 30 minutes a day, to get my heart rate up, and to sweat. I now do 5k every day on the treadmill and it certainly helps to keep my BS levels down. But we are all different, and you should do what you can cope with and build up gradually. A good low carb diet and regular exercise are your friends.
Posted this before but it's a good starting point: An easy walk lowers blood sugar level that's the basics - the fitter you are from regular exercise the more effectively your system handles insulin combined with good diet and you're well on the way.
Welcome to the forum! @gorillamark posted an article that works for me. In my experience, walking ( even light to moderate) 20-30 min on the treadmill after meals curbs the blood sugar down. From a peak of 6 goes back down to 4. Same with cycling and other cardio activities. But when I do intense weight training/strength with my personal trainer, my sugars go up but then goes back down after two hours, then in the afternoons I get to maintain low numbers. I exercise everyday, 30 min to an hour. Everyone is different, here in the forum a lot of people have bought themselves a glucometer to test their sugars before and after eating, and before/during/after exercise too. What people have recommended here is the SD Codefree from Amazon or eBay for the meters. (personally I'm using a Freestyle Lite Meter.) You might want to do that as well and check how your BGs react before/during/after exercise. So far, I've been able to maintain good blood glucose control with the aid of exercise (and a low carb diet---watching my diet via myfitnesspal app on IPhone) averaging at high 3s to low 4s for out of bed/pre meals and post meals at 4.7 to 5.2 (average). I used to have high numbers and now I'm off the metformin. Hope that helps!