Prepare the fruits: Cut watermelon into bite-sized cubes and place in a large mixing bowl. Rinse strawberries, remove stems, and slice in half. Toss strawberries and mixed berries into the bowl with watermelon.

Make the dressing: In a small bowl, squeeze lime juice and whisk in honey or agave syrup if desired. Let it rest to allow flavors to meld.

Combine the ingredients: Pour the lime dressing over the fruit mixture and gently toss to coat without breaking down the fruit.

Garnish for extra freshness: Tear fresh mint leaves and sprinkle over the top. Add chia seeds if using and toss lightly.

Serve and enjoy: Serve immediately or refrigerate for 30 minutes to chill before serving.