All one has to do is to allow about a tablespoon of saliva to build up in the mouth and hold it there for a period, whilst visualizing oneself without the problem e.g. if one had eczema on the hands, see them as normal. If one is not very good at visualization, one can tell the body to return to its natural balance instead.
If one needs to talk, drink, and so on, just swallow and then start again, there's no need to concentrate the whole time, if one holds the saliva in the mouth for an hour visualizing five or six times for thirty or forty seconds, that would be OK, though the more often the better, but one can get on with one's life.