This concept uses the environment to show how healthy the product is. Yoga studios are very much associated with health.
The setting would be a full yoga class, each member with a holder for their Fiber One bars to stand up on the front of their mat. The short ad could be as simple as them bending over for downward dog and taking a bite of the delicious treat. The long ad could have a dialogue encouraging the students to pace themselves when indulging in a Fiber One.