In a bowl, mix the chicken strips with lemon juice, olive oil, cumin, paprika, red chili powder, salt, and black pepper.
Let the chicken marinate for at least 30 minutes.
Heat a non-stick pan.
Sauté the sliced onion and bell peppers until they soften slightly and become tender.
Add the marinated chicken strips to the vegetables and stir-fry until the chicken is completely cooked and golden.
Serve the fajitas hot with whole wheat tortilla wraps.