I like to lie to myself - Brain, we are just going to run this 10th of a mile, then we can have a little break. Oh sorry, did I say just till 3.1 miles, no I meant 3.2 miles, sorry about that. Did I say we'd walk at 3.2? Sorry I meant 3.5, my bad!!!
So perhaps say to yourself - well I'm just going to put my workout gear on and stand in front of the mirror to see how it looks. Then say to yourself, "Well I'll just go to the gym to see who's on reception today, we'll maybe poke our noses in to see if the cute trainer's around." I suppose while you're there you might as well get on the eliptical for a few seconds, so you don't look silly walking in just to check the trainer out!
See how it goes....?