The Walk The Line star - who has three kids - was pictured chatting on her mobile phone while clutching a healthy green juice drink on Tuesday, 7 April.
Reese was dressed in Sweaty Betty gym gear - and looking fantastic!
She once told Us Weekly: "I work out all the time anyway just to stay healthy. I don't believe in crash dieting or anything like that."
And she's spoken often about switching between gym workouts with running alongside friends.
Reese and husband Jim Toth celebrated their four-year anniversary two weeks ago, with Reese marking the occasion on Instagram: "Four years ago, I married this amazing man from Pittsburgh, PA. He makes me laugh every day. I'm a very lucky lady. Here's to many more happy celebrations, JT! #HappyAnniversaryHubby."
They are parents to son Tennessee, two, while Reese also has daughter Ava, 15, and son Deacon, 11, from her marriage to Cruel Intentions co-star Ryan Phillippe.
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