Ich Vais Shoin Alles –
A chumra is a geder that chazal did not require us to make.
One is allowed, and should be machmir, when he knows that this chumra will be healthy for his growth in halacha and will not stifle him or other people in this or other areas. One has to know him/herself very well to make such a judgment.
A rav is not merely someone you consult for psak. A rav is someone who from his end knows you and your capabilities, and has the capacity and the qualifications to make sound judgments about how you should be living your life. From your end he is someone who you trust as such, and you consult him whenever you are unsure about any matter that concerned your yiddishkeit. That being said, if you don’t have a rav you are like a blind man groping in the dark. Find one, even if it takes a lot of work, because unless you are qualified yourself it’s the only way to do it right.
Saying a ba’al nefesh should be machmir means that halachically there’s nothing wrong, and most people are not holding by making themselves this geder that the halacha does not require, but a ba’al nefesh is holding there and therefore should.
Shoin du vaist alles…