If you have arthritis, it’s important that you keep moving.

That’s the upshot of a new study that found exercise can lift the mood of people suffering from pain and fatigue associated with arthritis.

Fatigue is one of the most common symptoms of both rheumatoid arthritis and osteoarthritis, which is common age-related arthritis. Many arthritis patients also suffer from depression.

A team of New Zealand researchers looked at a group of 142 arthritis. Of the group, 72 patients had rheumatoid arthritis and 70 had osteoarthritis, and measured the effect of daily activity and mood for seven days.

The study discovered that on the days when patients were physically active, their mood was much more positive, and that this association held true even when patients were feeling tired.

The researchers suggested that the positive mood might result from the fact that physical activity increases endorphins, a hormone that triggers positive feelings.

The study appears in the journal Arthritis Care & Research.