Keelin earned his Doctor of Physical Therapy (DPT) degree and went on to complete a year-long fellowship in Sports Physical Therapy and Orthopedic Manual Therapy, which led to his recognition as a Fellow of the American Academy of Orthopedic Manual Physical Therapy (FAAOMPT). He also became a Certified Strength and Conditioning Specialist (CSCS) over 10 years ago, further expanding his expertise in strength training and rehabilitation.

Driven by a passion for teaching, Keelin began working as an adjunct faculty member at the Massachusetts General Hospital Institute of Health Professions (MGH-IHP). In addition to his teaching role, Keelin is a credentialed clinical instructor with the American Physical Therapy Association, mentoring students and clinicians in clinical settings.

Currently, Keelin serves as the coordinator for the Johns Hopkins Sports Residency Program, where he provides mentorship and education to residents pursuing advanced specialization in sports physical therapy. He is also dedicated to health equity and inclusion. Keelin co-authored the article "Using Structural Competencies for Faculty and Students to Integrate Principles of Social Justice and Health Equity into a Doctor of Physical Therapy Program," published in the Journal of Physical Therapy Education. Additionally, he teaches a course on transgender healthcare at MGH-IHP, further demonstrating his commitment to LGBTQIA+ healthcare and inclusive practices.

With extensive experience working with athletes of all levels, including high school, collegiate, and elite athletes, Keelin has a particular interest in barbell sports—such as weightlifting, powerlifting, CrossFit, and physique training. He has also worked as a personal trainer, specializing in guiding individuals through post-rehabilitation strength training and helping them return to sports and active lifestyles.