盛(さか)りpeak (e.g. of cherry blossom season), height (e.g. of summer), prime (of one's life), one's best days, rutting, being in heat

僕(ぼく)にとっては十(じゅう)代(だい)後半(こうはん)が人生(じんせい)の盛(さか)りだった。

For me, the late teens were the prime of my life.

１０(じゅう)月(がつ)に入(はい)って暑(あつ)さがようやく盛(さか)りを過(す)ぎました。

Entering October, the heat has finally passed its peak.

多(おお)くの人(ひと)が人生(じんせい)の盛(さか)りを過(す)ぎたと認識(にんしき)する５０(ごじゅう)代(だい)が私(わたし)の人生(じんせい)の盛(さか)りでした。

For many people, the recognition of being past their prime comes in their 50s, but for me, it was the prime of my life.

本来(ほんらい)なら身長(しんちょう)が伸(の)び盛(ざか)りであるはずの時期(じき)なのに私(わたし)の身長(しんちょう)はなかなか伸(の)びない。

Despite this being the time when height should be at its peak of growing, my height isn't increasing much.

家(いえ)には食(た)べ盛(ざか)りの子供(こども)が三(さん)人(にん)もいるので毎月(まいつき)の食費(しょくひ)が嵩(かさ)んで仕方(しかた)ありません。

Since there are three children in the family who are in their growth spurt and always hungry, our monthly food expenses are quite high.