Frankie Valli Responds to Concerns He's Forced to Perform at 90

Frankie Valli sparked a public wave of worry after appearing disoriented and frail during a recent gig -- but he's clapping back, insisting nobody's twisting his arm to perform, and he's on stage by choice.

The 90-year-old icon's clearly fed up with the online chatter, even facing accusations of elder abuse against his team. But he’s setting the record straight -- it’s all him, and he feels blessed he's still in the game and doing what he loves at his age.

He told People the accusations crack him up ... reiterating on his own terms, "Nobody has ever made me do anything I didn't want to do."

Frankie’s all about that Four Seasons magic ... saying as long as the fans keep showing up, he’s in it for the long haul, promising to be "like that bunny on TV, just keeps going and going and going. Chasing the music."

There's been a huge concern for Frankie, with some videos showing him appearing to lip-sync to his own music onstage, and fans have been commenting about how exhausted he looks.