For many daily sessions and programmes (e.g. "strength") you can adjust your personal fitness level.
Step 1: In the "Discover" section scroll down to "Movement"
Step 2: Select a category, e.g. "Endurance"
Step 3: At the top of the overview you will find the fitness level
Step 4: Tap on it and move the slider to the right or left to increase or decrease your fitness level. Confirm.