I read Heal your Life by Louise Hay and something she said has affected me.So much so I consciously make an effort to replace SHOULD which is a certainity with COULD which is a possibility.I have been made fun of by my friends to whom above sounds totally bizzare.For me the logic behind this is when everything is uncertain,past is gone future is gonna happen when it happens then to live in the present one must live in possibility which I feel is positive.Using could is also in a way setting boundaries.If we were to ask someone for a favour could will be like asking politely and using should would be instructing them to do something which may no longer remain to be a favour.
Love to hear ur comments on the same.