Of course, this isn't to say that it can't be possible without the Apple Watch. It's just that it's more difficult to ignore.
I exercise intensely at least 3 times per week. If you achieve your move goal 5 times per week, the Apple Watch software will automatically raise your move goal the following week, giving you the option to manually adjust it on the start of a new week. Because I let the software take its automatic course, my move goal at one point was 1160 calories.
So, when winter weather came as well as a period of work crunch, I simply couldn't spend the 2.5 hours/day biking to hit that move goal.
Since then, my move goal has gone up and down, my higher goals coinciding with better weather and longer days.
Long story short, hitting one's move goals for many weeks on end implies the wearer is manually adjusting the move goal down each week.
e: Not so much about forgetting, but a nag.
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 :)