To approach a problem, obstacle, or challenge with supreme confidence of success through a commitment to use all facilities available to one's self to achieve a goal.
The term has etymological roots in the basketball parlance that describes an attempt to score in the crowded and highly contested area directly under and immediately adjacent to the raised hoop on a basketball court, or "painted" area. Shot attempts in this area are traditionally only successful when made with a strong conviction to score, skill, overpowering strength, or a combination thereof (i.d. "going hard").
When we saw Dason had put on his best suit and matching Tag Heuer timepiece, we knew he going hard in the paint to his job interview that afternoon.