• Written informed consent prior to any study-related procedures.

• At time of study are a young adult, aged 18-39 years.

• Histologically diagnosed brain tumor during childhood (diagnosed ≤18 years).

• Are at least 2 years post tumor-directed therapy.

• The effects of exercise on the developing fetus are unknown. For this reason, women of child-bearing potential must agree to undergo a pregnancy test and to use adequate contraception (hormonal or barrier method of birth control or abstinence) prior to study entry and for six months following duration of study participation. Should a woman become pregnant or suspect that she is pregnant while participating on the trial, she should inform her treating physician immediately.

• Medically cleared to participate in exercise by their referred physician or a certified clinical exercise physiologist.

• Are without medical conditions that could exacerbate with exercise, such as bone disease (excluding bone metastases) at imminent risk of fracture or uncontrolled cardiopulmonary or metabolic diseases.

• Speak English and/or Spanish.

• Currently participate in less than or equal to 60 minutes of moderate or vigorous structured exercise/week.

• Does not smoke or vape (no smoking/vaping during previous 12 months).

• Willing to travel to DFCI for necessary data collection.

• Ability to understand and the willingness to sign a written informed consent document.