Researchers have documented that just 5 minutes a day of physical exercise in a pleasant natural environment (urban parks qualify) is beneficial for mental health (in addition to the benefits of exercise in any environment.)  Read this article on the benefits of green exercise if you need one more reason to make time and get out into the natural world.  If you're looking for inspiration, consider joining WHAS for a volunteer or field trip activity.  The researchers encourage folks to self-medicate with outdoor exercise; birding as medicine!