I'm 39 y/o, I'm 295 pounds.. I was 385 may of 2019, 325 Nov of 2020. I bought a treadmill last week and been working out at 2.5mph.. Today I picked up the pace to 3.0 for 45 minutes. It was hard. I'm far more tired.. And I found out I only burned like 10% more calories than at 2.5. Doesn't seem all that worth it so going back to 2.5mph but bummed 3.0 was so much harder and hurt so much. I figured that much more effort would have resulted in a bigger caloric loss, so rather bummed out today.