"It feels good, really good," Headley said before the Padres opened a three-game series against the D-backs at Petco Park.
Headley, who suffered an injury to the same calf in an infield drill in Spring Training, said the extent of this injury wasn't nearly as bad.
Headley left a game on April 24 against the Nationals after straining the calf running to first base. He knew right away this wouldn't be like the injury he suffered during February when he needed crutches to get around the day after suffering the strain.
There was some confusion last week if the strain Headley suffered in spring was to his left calf, but it was indeed his right calf again.
Headley is eligible to come off the disabled list May 9 and could be ready after getting some at-bats and playing time in the field next week, either for Class A Advanced Lake Elsinore or Triple-A El Paso.
"It feels good, so there's no reason to sit around," he said.