Started exercising on treadmill, male, 31 i get my heart rate to 150-180. i do an hour per day. how long will it take at this rate to increase fitness and stamina?

You should start seeing some benefit after 3 weeks, more after 3 months and at that point doing it 30 min/day /360 could maintain & gradually increase overall benefit. Healthy nutrition and adequate restorative sleep remain as important in your overall hope to improve general health & stamina.

Agree with Dr. Ferguson. You could get much of the benefit with exercising for 150miutes/week. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Wish you good health!