When the contracts, the corner of the mouth is drawn upward and laterally when laughing.

zygomaticus Major

Explanation:

The Zygomaticus major , is one of the muscle of the human body , it is one the facial muscle responsible for smiling or laughing . Like other muscles responsible for facical expressions , the zygomaticus major is also innervated by the facial nerves.

The zygomaticus major extends from our cheekbone to the corners of the mouth.

Basically ,

When the Zygomaticus major contracts , the corner of the mouth is drawn upward , during the process of laughing.

answer: every other day

explanation: because you don't want to over work your body and especially if your just starting to work out.