“When William Penn was convinced of the principles of Friends, and became a frequent attendant at their meetings, he did not immediately relinquish his gay apparel; it is even said that he wore a sword, as was then customary among men of rank and fashion . Being one day in company with George Fox, he asked his advice concerning it, saying that he might, perhaps, appear singular among Friends, but his sword had once been the means of saving his life without injuring his antagonist, and moreover, that Christ has said, “he that hath no sword, let him sell his garment and buy one.” George Fox answered, “I advise thee to wear it as long as thou canst.” Not long after this they met again, when William had no sword, and George said to him, “William, where is t hy sword?” “Oh!” said he, I have taken thy advice; I wore it as long as I could.”
This link says this is a Quaker fable. That piece of information doesn’t make the story any less useful.
Do whatever it is that is fretting you for “as long as thou canst.” and when that becomes intolerable, do something else.