About Us


I’ve had personal trainers for 10 years; Brandon has outshined all of them and helped me produce the results I have been looking for.

Lester (MD), Age 72

My program with Alexandra provided education, wonderful support, and great instruction. It absolutely helped me meet my goals.

Timothy, Age 33

ON-CORE Fit is the joint collaboration of Brandon Thibodeau, a Certified Personal Trainer, and Alexandra Mark, a Registered Dietitian. Having both fitness and nutrition experts on your team eliminates the hiccups that can impede your success. At ON-CORE Fit we help you set realistic goals, and our team stays by your side each step of the way. We also provide the motivation and accountability that are critical components of lifestyle changes.
Brandon and Alexandra have over 15 years of combined experience in the health and fitness industry. Early in their careers, they recognized that many of their clients fell short of their goals by concentrating exclusively on exercise or diet. The key to success is a combined focus on food intake and physical activity, and that is what we offer at ON-CORE Fit.


At ON-CORE Fit we believe practicing everything in moderation and with balance is the backbone to achieve your goals and to maintain a healthy lifestyle. We are not asking to turn your world upside down, however assessing your eating and exercising habits to be compatible with your goals is extremely crucial in setting realistic expectations. We understand that we are all human and everyone’s body chemistry is different. That’s why it’s very important to be honest with yourself and your performance to make sure you are continuing on the correct path. With that said, we recognize that individuals have to live their lives and not deprive themselves entirely of foods they enjoy. At the end of the day, what you put into it is what you will get out of it. At ON-CORE FIT we can help you balance that fine line with full support.

Training Philosophy

We view the body as a single muscle, starting with the CORE, which is the foundation to your success. Viewing the body as one muscle and performing full-body exercise enables us to burn as many calories as possible in the shortest amount of time. An ON-going process of building and maintain a healthy CORE allows us to progress throughout all forms of functionality in a pain-free manner. This approach provides optimal results in stability, flexibility, strength, and endurance to reach the highest level of being FIT!!