lack of motivation or energy; a state of lethargy or apathy with low physical or mental drive.
最近、仕事に対して無気力で集中できない。
Lately I've been apathetic about work and can't concentrate.
風邪をひいてからしばらく無気力な日が続いた。
After catching a cold, I had several days of lethargy.
試験前だというのに無気力で勉強がはかどらない。
Even though exams are coming, I'm so unmotivated that I can't get any studying done.