First recorded by Marion Montgomery (1964).
Hit versions by O.C. Smith (US #127 1966), Frank Sinatra (US #4/MOR #1/R&B #25/UK #44 1966).
From the wiki: “‘That’s Life’ was written by Dean Kay and Kelly Gordon, and was first recorded in 1964 by Marion Montgomery. (Montgomery was born ‘Marian’ but later changed the spelling to ‘Marion’. According to spelling of her name on the single’s 45 rpm label, someone at Capitol Records didn’t get the memo.)
“The most famous version was recorded by Frank Sinatra in 1966 after hearing O.C. Smith’s 1966 cover arrangement, recorded shortly after Smith left Count Basie’s orchestra as vocalist. Released as a promotional single in February 1966, Smith’s ‘That’s Life’ ‘bubbled-under’ the Hot 100, peaking at #127.
“While not a Hot 100 national hit, Smith’s recording did enjoy regional popularity including the West Coast – and its radio airplay found interested ears. Sinatra first heard ‘That’s Life’ while out driving in Los Angeles listening to the radio. He stopped the car, called his daughter Nancy and told her to find the publisher of the song because he wanted to record it; she did; he did. Sinatra’s first public performance of the song was on his television special A Man and His Music – Part II broadcast in December 1966, with an arrangement by Nelson Riddle. Sinatra would record a studio version of ‘That’s Life’, after the TV taping but prior to its broadcast, for his 1966 album of the same name. The promotional single was released in November 1966, a month prior to the TV broadcast. The single would peak in the Top 5 of the Billboard Hot 100 and hit #1 on the Billboard Easy Listening airplay chart.”