After five decades in Hollywood, Henry Winkler points to his Happy Days costar Ron Howard as one of the best of the best - and it's not because he was a seasoned pro when they met. "I still participate on Twitter. I don't know for how much longer, but I do," Winkler, 80, told Woman's World editor-in-chief Liz Vaccariello on the inaugural episode of her "What Matters With Liz" podcast, noting that morning he had tweeted, "Ron Howard was one of the best acting partners I've ever had in my career.