Today is Martin Luther King, Jr. Day, a time to celebrate the birthday and reflect on the accomplishments and legacy of Mr. King. It is also a national day of service on which people are encouraged to use their day off from work or school to volunteer in their community. Individuals and groups across the country participate in community service, with some making this their first-time volunteer effort and many more continuing a year-round commitment to service.

You can maximize your impact in community service activities by being fit and healthy. To be sure, there are ways that people of all physical abilities can contribute, but some service opportunities require a baseline level of fitness to participate. And it is certainly more enjoyable to volunteer if you aren’t being pushed to your limits.

In fact, many service activities are similar in exertion to many forms of exercise and some may be consistent with maximal exercise. Unfortunately, the common pattern of inactivity and low fitness can limit people’s ability to function optimally at school, work or in leisure-time activities, including community service.

We classify the intensity of activities in units called metabolic equivalents, or METs. One MET is the energy expended sitting at rest, so other activities would represent multiples of that. For example, walking at 2.5 mph is about 3 METs and running at 6 mph is almost 10 METs. The MET values for hundreds of exercise, occupational, household, and leisure activities have been collected in the Compendium of Physical Activities.

Using this resource, the intensity of common community service activities can be determined.

For example, community clean-up efforts in parks and other public spaces often involve picking up trash, landscaping, and cleaning facilities. These activities generally range in intensity from 3 to 6 METs and involve lifting, carrying, and other whole-body movement, much like exercise. While people of all ages can participate in these activities, spending a full day does require a higher level of fitness.