In the Parsha of TZITZIS, the Torah Teaches us: "VE'LO SASURU ACHAREI LIVAVCHEM VIACHAREI EINICHEM - And you shall not stray after your heart and after your eyes".
Said Reb Lazer, VE'LO SASURU - you should not stray from the path of Hashem, ACHAREI LEVAVCHEM, V'ACHAREI AINEICHEM. The Torah is telling us, that even AFTER you already sinned, even AFTER you already started to go after your heart or eyes, DON'T CONTINUE the downward slide that the Yetzer Hara is trying to get you into even more than the sin itself!
So if you sinned, shake it off and continue on!!