I use a trainer when it's raining outside.
If you want an example of a motivated, disciplined cyclist have a look at 51 yr old,
Kevin Metcalfe's workouts during the winter. He's on the trainer every day for 1 hr with longer rides on the weekends. Seldom takes a day off.
If you limit your trainer rides to 1 hr they aren't that bad provided you have some music to distract you.