well, the question is about scruples, let me give you an example to see if this makes it more clear:
person A has scruples, so he has the tought that walking at that moment is a sin, it is of course not, but that person does not care and continues walking. does the attitude of person A made it sinful? or just like any scrupulous tought was just something made up in the mind and ought to be ignored.
A person with scruples - ought to have a “regular confessor” who can direct them. Such is the age old practice in the Church.
For ones scruples interfere with right judgement of conscience. One can become like a ship without a rudder. For a time at least one needs that regular confessor. One follows his direction (in what is not manifest sin -like he says go murder so and so -that one would not do). He knowing your particular difficulty can also give you general principles for you to follow.
Penitent: I have the thought that walking is sinful.
Confessor: That is a scruple -dismiss it and walk.
Penitent: But it seems sinful to me to do that.
Confessor: It is a scruple and your are to dismiss it and walk.
Penitent: But if I do I will sin.
Confessor: You will not. I am your confessor and you struggle with scruples - it is not a sin to walk -you are to go and walk and it will not be any sin.
Penitent: But is that not acting against my conscience? And something I should not do?
Confessor: No- it is a scruple. Your acting against a scruple under the direction of your confessor.
Penitent: But what if the thought happens still?
Confessor: Dismiss it. And walk. Scruples are to be dismissed not argued with.
Penitent: Should I then confess it if it happens next week?
Confessor: No. You are to walk and act against this scruple by walking - as your confessor has directed you. There is no sin and it should not be mentioned. You are to resist any urge to do so.
Confessor: And treat this scruple like a hissing goose or a barking dog -does one stop to argue with a hissing goose or a barking dog?
Penitent: No. You do not.
Confessor: Right - You keep moving down the path.