Personal Health Investment Today Act of 2021 or the PHIT Act of 2021 This bill allows a medical care tax deduction for up to $1,000 ($2,000 for a joint return or a head of household) of qualified sports and fitness expenses per year. The bill defines qualified sports and fitness expenses as amounts paid exclusively for participating in a physical activity, including (1) fitness facility memberships, (2) physical exercise or activity programs, or (3) equipment for a physical exercise or activity program.