I agree you can't do too much but timing is very important. You need rest time for your body to recover.
I vist the gym 5 days a week - on Mon, Wed, Fri I do a full cardio interval routine and weights and on Tues, Thurs just do 45 mins gentle cardio at about 70% heart rate. I see Tues, \Thurs as recovery days. Weekends are usually spent with family, sometimes doing "fit" things, sometimes not
Well that was until July when I had my heart attack! Now I just do gentle cardio and light weights 3 days a week but will get back to full routine as I recover. (Been told heart attck was due to diabetes complications - platlettes? - and if I hadn't been so fit it would have been curtains.)
One thing I noticed after I was first diagnosed is that my BS levels went UP when I exercised. For instance a typical level when I started exercising would be 6 but would be in the high 7s after training and stay there for a couple of hours. I found that some whey protein shake within an hour of the end brought numbers right back down.
Don't know the science behind it but worked for me.