This nailed it:
Quote Originally Posted by StephL View Post
Well - it only worked one time, but I just lately remembered one thing: If you prepare yourself mentally for it, you can wake up from the LD lying completely still, eyes closed, and try a re-entry per DEILD. The one time I really had planned on this, and one other time, this worked very well.
So that's not really about staying, but about not giving up, if you'd get indeed kicked out.
Need to urgently remember that. Usually one has a moment or two to think on this, before the dream actually ends.
I thought about how I keep from waking up during a LD, and realized after much reflection that I generally do nothing. If my body is set to wake up, and the dream is fading, I understand (and always have) that there is really nothing to do about it -- except set up for a DEILD.

I can remember a couple of very long and involved LD's where I just did not want to wake up and really tried to keep the dream alive, I only bought a few short minutes before my body's requirements took hold and the waking process interfered. The real answer to this question is twofold: first, try to do your LD'ing during times when you are not about to wake up (easier said than done sometimes, I know); and second, learn to DEILD, so you can allow your body to do its thing without losing touch with your lucidity or the dream.

[Note: this post was made without reading McWillis' posts, which were probably pretty good.]