I use the Strong app (free version, not pro). Contains lots of different exercises (bodyweight ones included), allows you to set up a workout routine, use it to log the workout including completed reps as you do them, and then report back on history, PRs, etc. Having a plan, having the ability to track progress, and making it easy to add variety to my strength workouts all helps with motivation in much the same way that the TR app helps with the motivation to do structured training.
And fully agree with the above statement that half the battle is just getting into the habit of doing it. Even if it’s just doing 10-15 minutes a few times a week it makes quite a big difference over time.