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.)
“O.C. Smith’s 1966 cover arrangement was 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 there found interested ears. Frank 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.