Your ds may take after you! And if he does, no amount of 'teaching' at 2, 12 or 22 will help.
Sorry... that sounds a bit brutal (and I'm not normally a brutal poster, honestly) but I think that you need to cultivate more of a 'whatever floats your boat' kind of an attitude. Your ds may end up being good at sports, like your dh, and that's great; but if he ends up with two left feet... well, that's just fine too, because he's bound to have other talents (as I'm sure you do) which you or your dh can help him to cultivate.
I write this as someone who is more hopelessly uncoordinated than the most hopelessly uncoordinated thing you can possibly imagine multiplied by a zillion. Sports days and even normal PE lessons were agony for me at school. It looks at if my dd1 is going to take after me in this (though at least she doesn't have milk-bottle-bottom specs, so can at least see the ball she is failing to catch/kick/hit), that it is just fine to be crap at sports and that it doesn't mean that you have to be a 'couch potato' either. Despite my general sporting crapness, I walked a marathon in June and I can also do a passable dressage test on a horse. There are other things your ds will be able to do to keep fit and healthy, even if he inherits your non-sporty gene.
My own parents were in total denial that their children were anything other than perfect [obviously I am nearly perfect ] and used to insist that I was good at sports (and not tone-deaf either... ouch!). This has just made me reluctant to trust other people's assessments of how good or otherwise I am at stuff (even stuff which I am objectively not bad at). So my approach with my own dds has been to focus on the positive, but not to deny that they may be less good at some other things. It's possible to do this without making them feel like failures, and, as I said, lack of sporting ability doesn't have to equate with blobby and obese, any more than tone-deaf has to equate with an inability to enjoy the music of others.