"My hands have become stiff and I can't do my job as well as I'd like to."
"My fingers"
"My fingertips."
"My hands have become stiff and I can't do my job as well as I'd like to."
"My hands have become stiff" 「手がこわばって」
"I can't ~" 「〜できません」
"do my job as well as I'd like to" 「仕事が思うように上手く」
"my hands" 「私の手」の代わり
"My fingers" 「指」または "fingertips" 「指先」も言えます。
[こわばる](https://eikaiwa.dmm.com/uknow/questions/109795/)ついてもっと詳しく知りたい方はクリックしてください。
Your fingers get stiff as you get older, so you're not able to do your job the way you'd like.
Your fingers become more stiff as you age, so you lose dexterity.
この場合、次のような言い方ができます。
ーYour fingers get stiff as you get older, so you're not able to do your job the way you'd like.
「年をとるにつれ手先がこわばるから、仕事が思うようにいかない」
to get stiff で「こわばる」
ーYour fingers become more stiff as you age, so you lose dexterity.
「年をとるにつれて先がこわばって、手先の器用さを失う」
to become stiff で「こわばる」
dexterity で「手先の器用さ」
ご参考まで！
オーストラリア 
カナダ 
