Cut chicken breast into 1-inch cubes and place in a bowl.
Combine olive oil, lemon juice, oregano, salt, and minced garlic in a separate bowl to create marinade.
Pour marinade over chicken and toss to coat evenly. Cover and refrigerate for 1 hour.
While chicken marinates, bring 2 cups water to boil in a medium saucepan.
Add rice to boiling water, reduce heat to low, cover and simmer for 18-20 minutes until tender.
Remove chicken from marinade and thread onto metal or soaked wooden skewers.
Preheat grill to medium-high heat and oil grates lightly.
Grill chicken skewers for 12-15 minutes, turning every 3-4 minutes until internal temperature reaches 165°F.
Let chicken rest for 5 minutes before serving over rice.