For bigger views and tougher climbs, test your legs on more mountainous territory. In 2014, Berghaus’s Steve Birkinshaw ran a continuous circuit of Alfred Wainwright’s 214 Lakeland hills in a record 6 days 13 hours, covering a huge 512km in distance and 36,000m in ascent. If that seems a touch too far, plot a short route which bags a few Lake District or Peak District mountains for a challenging run with incredible vistas.
There's also the Welsh 3000s Challenge: 15 peaks over 3,000ft in 24 hours. The task involves 30+ miles with 13,000ft of ascent and some dangerous rocky sections over the likes of Crib Goch and Tryfan, so confident scrambling and navigation is absolutely essential. The record, held since 1988, is 4 hours 20 minutes.
Tip: Fell running is notorious for unpredictable weather, so bring kit for absolutely every eventuality, including a head torch.