Rinse the chicken briefly in cold water and pat dry. Place in shallow glass or nonreactive dish.

In small bowl, combine garlic, lime juice, olive oil, agave, cumin and fresh ground pepper. Pour the marinade over and under the chicken breasts. Cover tightly and marinated for at least one hour, overnight is even better.

When the grill is hot, remove the chicken from the dish and discard marinade.

Grill the chicken over medium-high heat until it is cooked through and is no longer pink inside, about 12 to 15 minutes.