Preheat a non-stick skillet over medium heat and add olive oil.
Finely dice the onion, red bell pepper, zucchini, and garlic.
In a bowl, mix lean ground turkey with the diced vegetables, a pinch of salt and pepper, and tear in fresh basil leaves to form the meatball mixture.
Shape the mixture into small meatballs, approximately 1 to 1.5 inches in diameter.
Lightly brown the meatballs in the skillet for about 5-6 minutes, turning occasionally to ensure even cooking until they are mostly cooked through.
Meanwhile, cook the whole wheat spaghetti according to package instructions until al dente. Drain and set aside.
Add the marinara sauce to the skillet with the meatballs, reduce the heat to low, and simmer for an additional 5 minutes so the flavors meld and the meatballs finish cooking.
Toss the cooked spaghetti with the meatballs and sauce, garnishing with extra fresh basil if desired.
Serve warm and enjoy a delicious, balanced meal.