Heat 1 tablespoon of olive oil in a large non-stick skillet over medium-high heat.
Season the chicken cubes with salt and pepper.
Add the chicken to the skillet and cook for 5 to 7 minutes, stirring occasionally, until golden brown and cooked through to an internal temperature of 165°F (74°C).
Remove the chicken from the skillet and set aside on a plate.
Add the remaining 1 tablespoon of olive oil to the same skillet.
Add the zucchini and yellow squash slices; sauté for 4 to 5 minutes until tender-crisp and lightly browned.
Stir in the minced garlic, dried oregano, and red pepper flakes; cook for 1 minute until fragrant.
Return the cooked chicken and any accumulated juices back into the skillet.
Toss all ingredients together for 1 to 2 minutes to ensure everything is heated through.
Remove from heat, drizzle with lemon juice, and garnish with fresh parsley before serving.