Good advice from others, especially anything about starting real slow. Hell, you could even walk a few blocks before breaking into a jog. As long as you don't run first it doesn't count as Gallowalking.
As an older (39) guy with a tendency toward stiffness and inflexibility, I do some things to wake up / loosen up the legs first:
(a) coffee!
(b) work quads, hams/glutes, calves with "The Stick" - it helps warm/loosen those muscles and also gets your heart rate up, great little warmup
(c) no static stretches but I do just a bit of dynamic stretching. The Whartons (http://www.whartonperformance.com/index2.html) have this elaborate routine of a zillion stretches but I just do a few, for gastroc, soleus, groin, hams. The idea is to do 10 x ~2 second stretch - the claim being, anything over 3 seconds triggers muscles' stretch reflex so keep it less. I'm too half-assed to even learn the specific forms of the exercises the Whartons preach, I just adapted some static stretches (e.g. calves = wall push) with this timing.
The Stick & the dynamic stretches combined take me just a couple minutes and help noticeably. I know some my age who can just tie their shoes and bolt out the door at full speed every time but that'd spell injury for me pretty quick.