"It wasn't bad. I had a gauge of when I was coming in and was able to get ready and get myself loose," Upton said.
That didn't appear to be a problem as Upton had a single and stolen base in the eighth inning of the American League's 6-3 victory over the NL.
Facing Wade Davis of the Royals, Upton lined a single into left field on a 2-1 fastball. Upton then stole second base.
He became the first Padres player to have a hit and a stolen base in an All-Star Game since the late Tony Gwynn did so in 1989.
"That's cool," Upton said when told of his feat. "I wish it would have come in a bigger situation. But I got out there and had some fun and, overall, it was a good experience."
Upton's hit was the first for a Padre in the All-Star Game since Adrian Gonzalez got one in the 2008 game. It was also Upton's first All-Star Game hit in five career at-bats.
"When you're out there on the field, you're trying to do what you do and have fun with it," he said.
It was the first time Upton has played right field since doing so in 54 games with the Braves during the 2013 season. He's primarily been a left fielder ever since.
"It was a little bit of a shock at first, but once I went out there for BP I was pretty comfortable," Upton said of playing right field.
Now that the All-Star Game is over, Upton will head back to San Diego to prepare for the start of the second half, which begins Friday at Petco Park against the Rockies.
Upton and the Padres -- who are 41-49 at the break and 10 games back of the Dodgers in the NL West -- have some ground to make up.
"We haven't clicked on all cylinders enough. Lately, we've pitched really well and we haven't been able to support them as an offense. Before, we didn't pitch well and the other team got the big hit," Upton said.
"We're going to have to have a run where we are pitching [well] and the offense is clicking. ... We've got to score more runs and support our pitching staff."
Upton has done his part, hitting .253 with 14 home runs, 48 RBIs and 17 stolen bases in 87 games. He's played more innings (736 2/3) than anyone else on the 25-man roster.