parkrun — free weekly community runs (and junior events)

parkrun organises free, timed 5km events every weekend at parks and open spaces across the UK and free junior 2km events for children on many sites; everyone is welcome to take part regardless of ability. Participation is free — you register once online to receive a personal barcode, then attend a local event and have your run recorded; events are volunteer‑led and are a long‑standing, community‑focused way to get regular, no‑cost exercise and meet local people.