You are going to have to be very specific, and I don’t mean publicly on the Internet, but I mean in the confessional, when you speak of lust and impure thoughts and sexual desires with your confessor. Because there can be a wide spectrum of thoughts that are acceptable and thoughts that cross the line.
I often admire the feminine form of strangers or actresses and I can look for a good long time without even the slightest impure thought actually even crossing my mind. I do not allow myself to become aroused and I do not violate the chastity of these ladies in my thoughts, because those would be clear mortal sins for me. I do not feel that a gaze of admiration is anything to be ashamed of. However, I often confess a venial sin of objectifying women. I know well that my first thought should not be about a woman’s body, but it is a subconscious tendency that I have to appraise them physically to the detriment of personality or intelligence. But I do not think it is advisable or even possible for any person to abolish all thoughts of sex from his or her conscious, because, well, what can I say: it is a gift from God. There is a girl on the bus who is too young for me but has a marvelous head of long red hair. I consider it a gift from God when she rides and I can admire her hair and I can assure you that I don’t have the slightest inclination to sleep with her or undress her with my eyes or make a rude comment. I have a favorite actress and I must say that I am more attracted to her personality than anything else. But when I look at her and hear her voice I am overjoyed because she is the most beautiful thing to me - other than the Eucharist - and I thank God that she is a wholesome person who has found a great husband and had three children in a committed marriage. For quite a while my thoughts about her were persistent and obsessive, and I cured myself of this by mentally apologizing to her husband for my lust, and eventually the thoughts subsided to a manageable level.
Yes, I struggle with sins of a sexual nature, and in my past there are many mortal sins, but I promise that with a good confessor and a cultivated love for the Eucharist, you can overcome any mortal sin whatsoever, and it will never have a hold on you again.