Motivation is much like medicine. It's an outside in process and it suggests that the subject is lacking something.
Like a drug, attempting to motivate someone else, whether a pet, a teenager, an employee or a patient, requires that you overpower their current state. Worse, if you're able to move them to action, your efforts rarely last and you have to "motivate" them again. Attempting to motivate others is exhausting.
Instead, you and they would be better served by attempting to inspire them.
Inspiring patients is like chiropractic. It recognizes that what they need, they already have. But something is in the way. Uncover the interference (subluxation) and reduce it.
This requires sufficient curiosity to uncover that wee little "pilot light" of a dream, which when properly fueled and encouraged, can explode into a passionate fire. Do that each day and your practice will have no other choice but to grow.