Here's something to try. Buy some of those floss swords. Google it if you don't know what they are.
Place the floss sword so that the string is sitting in between your two bottom front teeth. This should prop your mouth open slightly and you should feel your condyle and jaw come down.
Play around with it to see what feels best and makes the most sense for your particular situation.
I do this while driving, watching tube, surfing net, playing games, and even walking around! As far as other people are concerned I just have a floss sword in my mouth - it's not that abnormal for people to walk around with toothpicks in their mouth!
Good luck, and keep trying new things!