Try putting him on a short leash in a sit/stay position, or down/stay position when you start to see someone approaching you. Stand in front of him kind of between him and the passing individual. if and when he starts to get up, give a correction and put him back into the sit/stay position. You want to get him in the sit/stay position before he gets all excited so that you can handle him. It might even help that when you have him in the down/stay position, to stand on the leash so he can't get up. when he stays in that position until the person passes, you then praise him. you can also give a treat if he is food oriented. you want to try and keep his attention to. if he knows the "look at me" command, you can repeat this several times to get his attention and then using a treat as a help, I did this with my dog and he got on to it in about a week. if you practice this on your walks everyday, he should pick it up rather quickly and eventually go into the down/stay position when he sees someone approaching.