pushing fifty

A Stranger is Watchingを読んでいます。
He stood up and streched. His shoulders and neck were tense and stiff. Pushing fifty and feel like I'm eighty, he thought. It had been a rotten day. Another attempted bank robbery... this time the Chase Bank at Forty-Eighth and Madison.
"Pushing fifty and feel like I'm eighty" 個所ですが、"Pushing" な５０歳だが、８０歳の様に感じる意味だと思いますが、この "Pushing" は押しが強い、つまり元気の意味でしょうか？　辞書を引きます。
・Merriam-Webster's Online Dictionary: marked by ambition, energy, enterprise, and initiative: among the young associates at the law firm, he was unmistakably the most pushing
・WordNet: marked by aggressive ambition and energy and initiative: A pushing youth intent on getting on in the world.
やはり、元気に溢れ、精力的な意味がありますね。しかし、それなら８０歳の様に感じるはずはありません。しつこく辞書を見るとありました、こんな意味が。
・Cambridge English Dictionary: be pushing 50, 60, etc.: He looks great and yet he must be pushing 60 by now.
・Dictionary.com: Used to denote that someone is nearly a particular (advanced) age : She is pushing 50 (1974+)
なるほど、これなら小説の引用個所は、まだ５０歳なのにと言う感じですね。