The apple barrel is a euphemism for your soul, your spirit. If you are constantly emptying the barrel to help others and leave nothing for yourself, then you run the risk, over time, of becoming bitter and depressed.
"This stage occurs when people are totally depleted, physically, emotionally, mentally and spiritually, and are unable to function."
Dr. David Posen Always Change a Losing Game
Many women, Moms in particular, but Dad's as well, fall into this pattern unconsciously, not realizing that their parental task is to raise children who can enter the adult world with all the emotional tools to succeed.
Always being there for them may make a Mom feel needed but that may not be what their child requires. They are in need of a role model who exhibits behavior they wish to emulate.
"As a teenager I was pleased to see my Mom not fall into this trap. She regularly did things for herself from horseback riding with girlfriends, to movie night with them to wine and appies while Dad took me out to dinner. This episode of "Young Sheldon" sends a great social message about a Mom's apple barrel becoming empty so she has nothing left for herself, a recipe for depression."