DMM is part of my daily routine, but there are days when I feel like I can't keep up with it.
I try to keep up with my studies at DMM every day, but sometimes I feel like I might fall by the wayside.
この場合、次のような言い方ができますよ。
ーDMM is part of my daily routine, but there are days when I feel like I can't keep up with it.
「DMMは私の日課だが、時々挫折しそうな日がある」
daily routine「日課」
I feel like I can't keep up with it. で「挫折しそう」を表現できます。
ーI try to keep up with my studies at DMM every day, but sometimes I feel like I might fall by the wayside.
「毎日DMMでの学習を続けるようにしているが、時々挫折しそうなときがある」
I feel like I might fall by the wayside. で「挫折しそう」とも言えます。
ご参考まで！
カナダ 
