When lacking in motivation, I make myself a “super polarized” plan consisting of Sprint Intensity workouts indoors, Z2 rides outdoors.
Sprints are 20-30 seconds long. I do them seated at 120-130rpm in ERG mode.
They are highly effective both anaerobically and aerobically and require less overall motivation because I’m able to tell myself, “I can do anything for 20-30 seconds.” The entire workout is usually only about half an hour.
Furthermore, I don’t have to nail every interval to feel like I accomplished something. In fact, the point the workout is to reach failure, as mentioned in the instructional texts. If you breeze through the workout, increase intensity on the next one.
I can do these 3-4X a week plus a couple outdoor Z1/Z2 rides.