After he felt numbness in his fingers after throwing Friday, he figured surgery was the only option.
"I think I had to prepare myself for the worst-case scenario," Beckett said Sunday. "And the worst-case scenario is just the time that I'm down. I've never had surgery so I'm not looking forward to it, but I was kind of preparing for that and if it didn't happen it would have been icing on the cake."
Beckett's condition is known as thoracic outlet syndrome, and he will have surgery in Dallas the week of July 8.
"We tried a lot of aggressive treatments," Beckett said. "I think this is going to put me in a better position than I was in."
Beckett is expected to be sidelined three to five months, which would put him back on the field in time for spring training.
The 33-year-old Beckett is making $15.75 million this season and is due to make the same next year. In eight starts this season, Beckett was 0-5 with a 5.19 ERA.
Dodgers manager Don Mattingly said the decision was made to have surgery so Beckett would just miss one season and his condition wouldn't linger and force him to miss next season as well.
"I don't know a whole lot about that surgery," Mattingly said. "I know it's complicated. I know [St. Louis Cardinal pitcher Chris] Carpenter had it and he came back and pitched a little bit and he had more complications. I don't know a whole lot about it, but I know from Josh's standpoint he didn't want to get into the winter with this. Optimistically, if everything went perfect he can be back in three months. He didn't want to wait and wait and wait and not be ready for next season too. You start jeopardizing two instead of one. Once he started having the tingling he knew."
Here are lineups for Sunday's game, with the Dodgers trying to finish their homestand with a 6-1 mark:
1. Michael Young 3B
2. Chase Utley 2B
3. Jimmy Rollins SS
4. Ryan Howard 1B
5. Domonic Brown LF
6. Delmon Young RF
7. Ben Revere CF
8. Carlos Ruiz C
9. Kyle Kendrick RHP
1. Skip Schumaker 2B
2. Yasiel Puig RF
3. Adrian Gonzalez 1B
4. Hanley Ramirez SS
5. Andre Ethier LF
6. Matt Kemp RF
7. A.J. Ellis C
8. Jerry Hairston Jr. 3B
9. Stephen Fife RHP