Personal experience: I got hooked on hitting my activity goals with my Apple Watch and am now on day 292 of my streak. I've lost 20 pounds and am running a 5k at a near 7min/mile pace, something I haven't done in over 15 years.
Sure: the watch didn't move my legs for me, but it sure as hell manipulated me into getting off my ass :)
Counterpoint, I never want to run at 6:30 am so having someone or something add pressure to get out only helps keep that commitment. And 15 min in I'm always glad I got out of bed.
Different things work for different people. My wife and I exercise very regularly, but the way in which we stay motivated and on track are very different.
e: Not so much about forgetting, but a nag.