1) One who accustomed himself to keeping a specific stringency, which is unnecessary according to the letter of the law, (for example fasting during the days when we say Selichos), if he intended to keep this stringency forever even if he had only actually done it once, or if he did it three times even without the intention of continuing it permanently, if he did not specify that his action did not constitute a vow, and he wants to stop performing that act because he is not healthy enough, he still needs to go to a wise man to repeal it. He should use the fact that he regrets ever having acted in a way which constitutes a vow as an opening to repeal the vow. (Kitzur Shulchan Aruch 67).
2) It follows that one who wants to perform a stringent act for a precaution or abstention, should specify at the beginning that he is not intending to make a vow. He should also say that he is only intending to do this act this once, or the specific number of times that he wants, but not forever. (ibid).