Originally Posted by jzmtl
So any good way to keep this from happening, or notice in time to correct myself? (other than get in better shape, lol)
Sure. Just get this.
Seriously, I've struggled with back seat issues, and when I first get out (and occasionally throughout the day) I'll do some one-legged skiing drills. They help me dial in being centered. Throughout the day when I get off the chair on the way to a run I'll make use of that space to stand tall and very lightly pressure the shin against the front of the boot. I know I've got it when I can make easy, smooth, swaying turns by gently rolling my ankles side to side. Skating and skiing one-legged on cat tracks also helps keep me centered.
I guess you were asking for something more real-time, that you can use as a check while you're in the middle of a run, but I find if I do those things regularly they help keep me on track and avoid the back seat. I'm a nobody intermediate, but even the best take a breather and do this kind of stuff to get the right feel back.
Bottom line? As others noted, when the spirit is willing but the flesh is weak usually best to quit and live to ski another day.
Easy to say here, of course. ;-)