I love watching a little YouTube as a reward after I've been working hard all day.
I was pegging away at a new project at work all week, so I rewarded myself with a big steak at my favourite restaurant when I finished it.
この場合、私なら次のように言います。
ーI love watching a little YouTube as a reward after I've been working hard all day.
「１日一生懸命働いたご褒美として、ちょっとYouTubeを見るのが好きだ」
to peg away は通常長い期間何かに取り組み続ける時に使います。
ーI was pegging away at a new project at work all week, so I rewarded myself with a big steak at my favourite restaurant when I finished it.
「１週間ずっと新しいプロジェクトに取り組んでいたので、プロジェクトを終え自分のご褒美に、お気に入りのレストランで大きなステーキを食べた」
ご参考まで！
カナダ 
