George Kattan
Definitely don't look at him while you're approaching, that is good advice. Bumping into him at the exact time that you say The Word/Phrase is key. Eventually (quickly) he will associate the bump with getting out of your way. If he is insanely food driven, you could bump/say it/toss a treat behind him (in front of you) until he figures it out.
Something that has helped, not just with my own dogs but with those for whom I sit, is to expect that I'm going to get the good behavior that I want. If I'm already thinking the negative, that's usually what we get. But if I set it up for the dog not to fail, everybody wins! Then mark the good behavior with "Yessss" or "Good" or something positive.