We can't do 90 days now. We can't even do 2 days now! Can we EAT or go to the bathroom for tomorrow?? We can only do TODAY. Forget about yesterday's slip, forget about today's slip, and forget about the future. The Pasuk says: "Ve'ata Yisrael Ma Hashem elokecha Sho'el Me'imcha - and NOW Yisrael (is) what Hashem asks of you". Ve'Ata: RIGHT NOW. That is ALL Hashem asks of us!
How freeing is THAT?