independent; autonomous; voluntary; of one's own initiative
independent training (e.g. of athletes working without a coach)
voluntary training; voluntary practice; free practice
voluntary restraints; self-limitation
independent production (e.g. of a film)
cutting class (esp. of university students)
voluntary recall (e.g. of faulty goods)
autonomous (national) defence; self-reliant defence
self-management; self-imposed control
voluntary liquidation; voluntary closure (of business)
voluntary withdrawal from school; dropping out of school of one's own accord
local disaster prevention organization
caring for oneself (at home; e.g. after testing positive for COVID-19)