I'm a bona fide insomniac. My mind constantly races and my body just gets exhausted trying to keep up. That's one big reason why I run - to expend as much energy as I can.
Activity does a lot of good in more ways than one, and promoting good, restorative sleep is one. A good mattress also helps, as well as not having animals in the room with you, or installing light blocking drapes over the windows (I still need to do that). I think that the evening walk for your constitution has a lot of merit.
I wonder how many people still go for the warm milk routine. My magic "sleeping pill" is a book. I can guarantee you that, as soon as I try to read one page, I'll fall asleep. I have no idea why, lol!