Where I live, theres a little cookie shop that advertises "Labor Cookies" and they worked within 8 hours for me, and 12 hours for my sister in law...plus numerous other ladies in town. All they have in them in spices of all kinds. So things like cinnamon, cardamom, ginger, cloves, and a few other things. So I would try to make some good 'ol fashioned spice cookies to help.
Also, riding in the car on a very bumpy, gravel road is suppose to start labor (so my OB says). Speed walking may help, but with your lungs compressed right now it may not be the best option. Lots and lots of sex is also suppose to help (my water broke just a couple hours after a vigorous roll in the hay so who knows if it was that or the cookies lol)
Sitting/bouncing on a yoga/birthing ball is suppose to help as well. Hope some of these ideas help you! If nothing else, you will feel better after eating some yummy cookies and good sex! lol