I leave the electricity turned off (throttle) unless a grade is bad enough to pull me down to 3 mph. Or if the wind in my face is bad enough to pull me down to 4.5 mph on flats. I hated cadence assist and pulled the crank magnet away from the sensor.
You may need more assist in the beginning until you build up your strength and wind. I rode unpowered for years, starting at 5 miles until I built up to 25 miles in my fifties. A windy day September 2018 convinced me to buy electric assist. My route between 2 houses is fixed, and 6 hours over 27 miles (4.5 mph) at 120-144 bpm is TOO MUCH EXERCISE. Winds are much worse now than in the 2010's even. Wind used to be pretty calm between May and the second week of October. Not any more.
I was an Army vet and transisioned from jogging per the Army program in my fifties to bike riding as my knees wore out. Other people may not have the heart+lung health to jump in radically an aerobic exercise program. Read Dr. Cooper's book Aerobics and do not run your heart over 75 bpm in the beginning. Exercise aerobically 30 minutes 4 times a week. Back off and see a physician if you ever feel faint or dizzy during aerobic exercise, or if your heart starts skipping beats. Stay in touch with a ride partner with a cell-phone while building up, you may need assistance. Barring medical problems you may be able to increase the safe heart rate about 4 bpm per month until you reach the rate Dr Cooper recommended 30 minutes 4 times a week. 85% of (200 - age) I remember it as.