One of the things that you notice about salt or sugar is that, as you consume more, you tend to get desensitized to the taste. You tend to need more and more of both of these to really experience flavor as time goes by. Lately, I've been trying to dial back my consumption of both of these things (though I actually don't eat a ton of sugar anyway).
I'm attempting to do this in a similar way to how I've slowly reduced portions. I usually put two packets of Splenda in my tea, I'm going to try and start cutting that back to 1.5 and see how it goes. I'm hoping to eventually reduce it to 1. For the record, two packets of Splenda is supposed to be as sweet as 4 tsp. of sugar, so that's pretty sweet tea. To be fair, I have large cups of tea (and tiny cups of coffee) because it's mostly water.
Similarly, with salt, I'm attempting to sample food which has already been seasoned to some small extent during cooking with salt before automatically pouring on more. If I really feel I'm not enjoying it or getting enough flavor after the first few bites, I'll add a bit more. With salt in particular, I'm finding that I don't need as much as I have been using and the taste is fine.
With sweetness, the adjustment is going to take some more time. Ultimately, I'd like to be able to enjoy something with honey or other less intense sweeteners and not have to pour it on massively to get the effect. If I can heighten my sensitivity to sweetness, I might also be able to cut back on calorie-free chemicals.
The biggest reason for doing this is to try and help my taste buds acclimate to more "plain" food. I think that we lose our sense of how delicious and acute the sweetness of fruit is once we become used to lots of external sweetening. With salt, I'm actually just concerned about the health effect, particularly with how it may contribute to the incidence of strokes and high blood pressure (though I don't suffer any issues at present, I'm old enough to start considering these possibilities).
As was the case with portion reduction though, I view this as an extended process. That is, I'm going to do this gradually over months (possibly a year) so that it doesn't feel jarringly different and I don't feel like I'm losing my sense of enjoying the food. I'll report my results here if anyone is interested.