...and the pounds will take care of themselves. It's brilliant advice, as these old sayings always are. Except, as old sayings always do, there is a near opposite in the phrase "penny-wise and pound foolish." We see something similar in the twin phrases look before you leap vs. he who hesitates is lost, echoed in both directions by strike while the iron is hot, make hay while the sun shines, haste makes waste - the list is endless. In retrospect, anyone can kick you and make you feel small for neglecting some important cultural lesson that you should have absorbed in kindergarten, or its reverse that you also absorbed in kindergarten. The classes you didn't take, the stocks you didn't buy, the boys you didn't kiss, the job you almost took, that can pain the nostalgic so deeply now, compounded by the stupid classes you did take, the dumb stocks you did buy, the jerk boys you did kiss*, the pointless job you did take...can haunt you unnecessarily.
Of course you did stupid things. Winston Churchill mostly bumbled until his shining hour. Moses had to be dragged kicking and screaming into the one job he was destined for, very late in life. I chuckled long ago that if I could go back with a carefully curated hour with my 17-year-old self, I wouldn't listen. I would absorb an idea or two and then mostly make the same mistakes again, only at different times and with different theme music in the background.
We made a series of ridiculous penny-wise and pound-foolish decisions on a trip to Massachusetts today. Eh. So what? That woman's life, and her daughter's, are much harder than ours. We just absorbed it, one of the advantages of age and mistaking tiredness for wisdom. However, seeing that it does in fact look so much like wisdom even though it is a mere imitation, we pass it on to you.
*I fear I figure prominently on that list.