The veteran actor was thrilled when Grace and Frankie was picked up for a third season - and then floored when he discovered how unhealthy he was during a routine physical.

"When we got the pick-up for season three, the producers told us we all needed to have a complete physical - blood tests, stress tests, the whole nine yards," Martin, 75, tells TV Guide magazine.

"And thank God for that, because I found out I was in really bad shape. I could have been dead on a sidewalk somewhere."

But his co-star Sam Waterson insists the comedy has extended his life and the lives of Martin and their TV wives Jane Fonda and Lily Tomlin - because they're always having a ball on set.

"Jane, Lily, Martin and I report for work and basically laugh our way through the entire day," he explains. "It's such a pleasure at this stage of our lives to finally be over it - over the business and especially over ourselves. We're just glad to be alive.

"The best, most marvellous thing about our show is that it's a reminder of how precious little time we all have."