Was it that you were looking for self-care, wellbeing, head space, strength...? Reflect on what it would feel like to have those things back in your life; and how has it felt without them.
Perhaps during your reflections, you might notice other things that you missed about your regular exercise routine, that weren't necessarily the reasons why you started. Maybe you're missing the community and laughs of your group; or it could be that you've realised that it gave a cadence and rhythm to your week that made you feel more grounded; or maybe it just gave you an hour to yourself.
Once you've reminded yourself of your "why", it helps you to find the reason why you should go back.