The 84-year-old presenter returns to anchor his 10th series of the BBC ballroom contest this autumn and the entertainer insisted that his family and friends wouldn't be afraid to step in if they thought he was no longer capable of hosting the show.
Bruce Forsyth - Career in pictures:
Copyright: Rex Features ITV"I will know it's time to retire," Forsyth told Daybreak. "My loved ones, my darling wife, my agent, manager Jan and Ian, they will tell me.
"I've always told them if I look as though I'm over the hill, you know, just tell me - but I think I'll know myself."
Forsyth was given a knighthood in 2011 and has collected BAFTAs, NTAs and RTS awards during his extensive career on television.
Vernon Kay, Anton Du Beke and John Barrowman have all been tipped by the tabloids at various times to replace Forsyth when he eventually retires from Strictly.
Strictly Come Dancing's first live shows will air in October on BBC One.