“Every sin is manifested in two different ways: it can happen only once, or you may fall into sin periodically, but there is also the state of passion when sin gets a lasting, firm grip on you. If, in the former case, we simply have to collect ourselves and, with prayer, continue working, then in the latter case our battle with sin, just as passion itself, becomes a battle for many years—possibly a life-long struggle.”
(Fr Alexei Taakh, orthochristian.com)