When does laziness become a sin?

[Whdevo]

Please be careful with such blanket statements! Not all sins of lust are mortal sins - if I look at a woman’s bottom because I think it’s shapely, that is, strictly speaking, a sin of lust, but not a mortal one because there is no grave matter.

Hi, I must strongly agree …

I recall from my Chatechism at school that:

A venial sin is any sin which we, ourselves, commit.

Whereas:

A mortal sin is any sin which we commit with full knowledge and full consent.

As to the initial question, I would humbly suggest that, whenever that voice inside tells you that “this isn’t quite right” and you ignore it, then, doing something that you know isn’t right, your action (or thought) would constitute a sin.

God Bless you

William