backslide
verb [ I ] uk/ˈbæk.slaɪd/ us/ˈbæk.slaɪd/ backslid
倒退，退步；故态复萌（尤指不再努力工作或不做承诺过的事）
to go back to doing something bad when you have been doing something good, especially to stop working hard or to fail to do something that you had agreed to do
My diet was going well, but I've been backsliding a little recently. 我的节食计划过去一直进展顺利，但是最近恐怕有点儿退步。