As with franko's answer, the reason why you use salt (preferably sea salt) is that it helps to crush and mince the garlic whilst you are chopping.  If you are worried about too much salt in your diet, then do not use any other salt than what is used whilst mincing your garlic.  Like above, I don't understand why you have to discard what is on the knife, I am assuming that you have peeled your clove.  If you are worried about cutting yourself, simply scrape the side of the knife on the edge of the board, gather it up into a little pile and carry on mincing, a bit of chop chop, then scrunch down with the sea salt.  As an aside to this, though this was always my preferred method in the past, I have now taken to grating garlic with the very fine part of a cheese grater.  This not only takes a second or two but also you don't have to peel your clove as the skin is left on the top side of the grater, whilst the grated garlic is on the underside.