Please advice regarding my physical exercise as I'm a physically challenged.?

Hi.. I'm a 30 yr old physically challenged man. I walk slowly with a caliper and walker. I want to be healthy in my life without any diseases like diabetes, hypertension, heart disease, stroke, etc. I could not do exercises like brisk walk, exer-cycle, treadmill, etc. I can walk slowly using my walker just for my mobility purpose but I could not do walking exercise continuously for more than 5 to 10 minutes. I can able to do some weight bearing exercise using dumbells. I can able to do this dumbell exercise for 30 minutes. When Im doing this dumbell exercise, I dont sweat but I try to give my full effort for half an hour. I dont know whether my heart beats fast or not while doing this dumbell exercise. Now my question is... If i keep on do this dumbell exercise alone(which alone I could do) will I be able to prevent from the above said diseases? Also, Im not over weight and Im under diet control. Pls advice.