Jaw Angle Implants
Exercise if not going to increase your masseter muscle size any appreciable amount. And even if it could the muscle size could not maintained. Jaw angle implants are your best option for a permanent lower facial width increase.
Candidate for a Chin Augmenatation
Without an exam your question cannot be answered. However, your photos are helpful and you are probably a good candidate for a Chin Augmentation. You will need to see an Oral/Maxillofacial surgeon to see if othognathic surgery, genioplasty or using an implant is best for your specific case. It should be noted that patients with severely weak jaws or abnormally functioning jaws may be better treated with other facial surgery (orthognathic surgery), although a chin augmentation may be an option at a later time. These patients should seek the advice of a plastic surgeon to determine which course is right for them. Here is some information to help you make this decision: Candidates for Chin Augmentation - Patients whose chin profiles are weak but have normally functioning jaws are candidates for Chin Augmentation. Many of these candidates have used injectable fillers in the past to strengthen the protrusion of their chins, but are looking for a permanent solution. If you are one of these patients, then you are a likely candidate for chin augmentation