hi elk,
somebody else recently posted that they will say, "I'm just going to go out for 15 minutes and then I can come home if I want." I do this with both running and biking sometimes when I'm having trouble getting motivated.

Usually by the time I"ve reached the mandatory number of minutes/miles, I have already started to get into my run or ride and am enjoying it... I don't think I've ever actually turned around. Sometimes it's helpful to give yourself permission to go really easy too, even to tell yourself you HAVE to go really easy.

Getting out the door is the biggest obstacle...

Good luck!