I agree with you, but I think the parent was saying that even controlling for one's ability to successfully do a thing, some things (i.e. those that are more st

I agree with you, but I think the parent was saying that even controlling for one's ability to successfully do a thing, some things (i.e. those that are more strenuous or otherwise require more commitment) take longer to solidify as habits, which makes sense if we think of habit-forming as environmental adaptation. One doesn't adapt to massive environmental changes after just a couple of weeks.