As Young as You Feel (1951) on Netflix

Skilled printer John Hodges is stunned when Acme Printing forces him into retirement at age 65. His family can barely stand having him at home, and the traditional pursuits of the aged do not appeal. Enter a charismatic impostor: Hodges disguised as Harold Cleveland, president of the parent corporation, to make a slight change in company policy. But Hodges, riding the tiger, finds it's not so easy to get down... especially when his ex-boss's gorgeous wife falls for him.