I know. But you had so far made no distinction between the two and were definitely trying to link them. The labor force participation rate is the number of people in the labor force (employed plus unemployed) divided by the adult civilian non-institutional population (those age 16 and older excluding active duty military, prisoners, and those in long term health care or nursing homes)
You are thinking instead of Not in the Labor Force, which is everyone who is neither working nor looking for work. That number is mostly people who do not want to work, and the majority are old, disabled, students, or stay home spouses. Also included would be the independently wealthy, many criminals, and potheads living in mom's basement.
Most of the changes to the participation rate are demographic, not economic.