When you get the things you have to do finished with, it feels good, doesn't it?
When you are done with whatever that you have to do, it feels good, right?
ご質問ありがとうございます。
① "When you get the things you have to do finished with,"＝「やらなきゃいけないことを終えると」
"it feels good, doesn't it?"＝「良い感じだよね？」
② "When you are done with whatever that you have to do, "＝「しなければいけないことを完了すると」
"it feels good, right?"＝（①と同上）
ご参考に。
You feel much better when you take care of the things you need to first.
It feels good to finish the things you have to take care of.
ーYou feel much better when you take care of the things you need to first.
「やらなければいけないことを先に片付けるとすっきりする」
to feel much better で「ずっと気持ちが楽になる」
to take care of ... で「…を処理する・片付ける」
ーIt feels good to finish the things you have to take care of.
「片付けないといけないことを終えるとすっきりする」
to feel good で「気が楽になる・人を満足な気持ちにさせる」
ご参考まで！
アメリカ合衆国 
カナダ 
