National Polish Health Test is an online study conducted on a large group of Polish Internet users. For the purpose of this study, 64,732 subjects (48.8% female) over 65 years old were included. Subjects provided answers on the level of physical activity (PA) they engage in, prevalence of non-communicable diseases (obesity, hypertension, diabetes, heart diseases, chronic obstructive pulmonary disease (COPD), depression, cancer) and subjective physical and psychological health. Additionally, their Body Mass Index (BMI) and prevalence of multimorbidity was assessed. We found that older people who engage in at least 2 h of physical activity/week had significantly lower prevalence of hypertension, obesity and heart diseases than those who engaged in 1–1.5 h/week or less than 1 h/week. Multimorbidity was present in 33.2% of subjects from the most active group and 52.6% of the least active ones. Subjective physical and psychological health was rated as “very good” by 26.6% and 41.2%, respectively, by subjects from the most active group. Only 9.1% of the least active subjects rated their physical health as “very good” and only 27.4% rated their psychological health as such. Regular physical activity may be a helpful tool in combating the reduced well-being of older people affected by the isolation caused by the COVID-19 pandemic. Unfortunately, over 65% of respondents claimed to engage in less than 1 h of PA a week or less.