Garmin always says I lack high-intensity aerobic exercise, so
I asked AI and it said I need to ride at zone 3~4 for over 20 minutes to increase my high-intensity aerobic exercise.
I used to ride at 120, but I increased it to 160 and rode in intervals, which was definitely hard and tiring.
This week I was tired so I slowly rode and went to sleep, and my average power increased from 120 to 130 lol