Seems like you are tying your shoes wrong. If you do it just a bit differently the knot will be horizontal on the shoe and tighten itself. Just do the loops over each other in the opposite order.
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I learned this a few years ago and it works great. It's called a reef knot and it does take a minute getting used to going under rather than over but, if tied correct the knot will actually tighten the more its worn.
The knot above is tied this way and it looks great.
I don't remember who taught me to tie my shoe when I was a kid, but they taught me correctly...
There is a simpler way of getting the same result. Instead of switching the orientation at the loop stage of the knot, you tie the first overhand knot in the different direction, and then do the loops as you normally would. (In case you are currently tying your shoes incorrectly and have grown used to doing so.)