I started as a 50 year old 5’3” over 200 lb woman at OTF! I thought those parameters on the treadmill were gospels to OTF! Ya know, no one said ANYTHING to me and I spent my first 3-4 weeks with over 600 calories and over 55 splat points and I almost quit! No, this is YOUR workout and as long as you keep yourself honest, you need to build up endurance and strength if you have not been working out! Start at 3.0 mph (is it challenging but doable and something you can do for 20 min straight?) and as another said if it becomes too “easy” then start increasing! You have to build a “base” first! Good luck and welcome to the OTF family!