Independent; autonomous; voluntary—done by one's own initiative.
彼はいつも自主的に仕事を見つけて動くタイプだ。
He's the type who always finds work to do on his own initiative.
この課題は自主的に取り組むことが求められている。
This assignment requires that you work on it voluntarily/independently.
自主的な判断が評価された。
Her autonomous judgment was appreciated.