This is the 8786th most frequent Japanese word.
本腰
"本腰" means serious effort or full commitment.
In this sentence, '本腰' refers to serious effort or commitment put into an activity, as the subject begins to take the project seriously.
彼はプロジェクトに本腰を入れ始めた。
He started to put serious effort into the project.
Here, '本腰' is depicted as the requirement of serious commitment and dedication needed for success in a specific task—studying for exams.
本腰を入れて勉強しないと試験には合格できない。
You won't pass the exam without making a serious commitment to studying.
In this example, '本腰' emphasizes a strategic decision to devote focus and resources to an endeavor, highlighting a deliberate action to prioritize.