Formula: Days since record was last updated

Hi again.

I´m trying to calculate how many days since a record (Opportunity) was last updated. I know there is a KB about this but the example there is calculating between two date fields on the record. I need to calculate between now (today) and $date_modified. Here is my attempt (which returns a blank):

abs(subtract(daysUntil($date_modified),daysUntil(now())))

Is this maybe not possible?

Only possible to calculate/count between two date fields (not a date field and now/today) as mentioned in the KB...

Thanks guys,

KGM