by Stephen Thomas ErlewineJohn Mellencamp responded to his massive heart attack and close-call with death with Mr. Happy Go Lucky, the most overtly ambitious album in his career. Mellencamp has always been a bit of a fatalist, so it isn't any great surprise that there is an undercurrent of dark mortality running through most of his songs. What is a surprise is his musical approach. Although he hasn't abandoned the essential elements of his music -- the rootsy instrumentation, the violins, the simple song structures, the gritty folk-rock -- he has augmented it with the help of Junior Vasquez, a noted dance producer. Vasquez doesn't push Mellencamp into dance, but he adds certain dynamics and techniques from club music to Mr. Happy Go Lucky which ocasionally gives the album a greater depth. It's a gentle change, not a forceful one -- nothing sounds like dance music, but there are deeper rhythms and bass throughout the album, which breathes life into well-crafted songs like "Key West Intermezzo." Since he doesn't pursue dance completely on Mr. Happy Go Lucky, Mellencamp doesn't end up alienating his fans, but the reluctance to give himself over to dance makes the album uneven. Ironically, the tracks that exhibit Vasquez's influence the least are the least successful -- they simply sound like Mellencamp is going through the motions. Nevertheless, Mr. Happy Go Lucky proves that Mellencamp has more surprises in him than many listeners would have expected and suggests that he is in the process of revitalizing his career.