Cube the watermelon into bite-sized pieces and place them in a large mixing bowl.
Slice the cucumber into thin rounds and add them to the bowl.
Crumble the feta cheese and sprinkle it over the watermelon and cucumber.
Chop the fresh mint leaves and add them to the salad.
If desired, drizzle a bit of olive oil and squeeze in fresh lemon juice after mixing the fruit and before tossing everything together.
Gently toss everything together to combine.
Taste and adjust with more salt, pepper, or lemon juice if needed after chilling the salad for 10–15 minutes to allow the flavors to meld.
Let the salad chill in the fridge for about 10-15 minutes for the flavors to meld.
Serve chilled as a refreshing snack, side dish, or light meal.
Garnish with extra mint leaves or lemon zest before serving.