Sammy Hagar has learned to roll with the punches, as befits a former boxer turned Rock & Roll Hall of Fame inductee who in 1995 was fired from his decade-long gig as the lead singer in Van Halen. The veteran solo star has also learned to stay extremely active, on stage and off. “I’m about as busy as a man can be — and I don’t know why. I’m confused!” Hagar said, speaking by phone recently from his Marin County home. How busy? Here are some examples.