6 minute miles are quite speedy for most runners. Hate to patronise but you keep mentioning 5k... are you sure it wasn't Minutes Per Kilometre you were using? In which case 6 min km will feel easy and slowI did a really subpar workout today so I figured lets do a 5k as I haven't ran properly in a week apart from sprints, I started running and checked my phone towards the end of a mile and seen I was on 0.9miles at 5.5m/m pace and was like WHATTT. Seeing as my last best 1 mile time was 6m 48. I think I am going to try to go even faster tomorrow and get the 1.5miles done. Part of this run is a tiny bit of downhill so I thought maybe it's cheating ahaha but I don't think I'd have been much slower on a flat surface. It just confirms to me how much your mind plays with you. I literally did sprints the other day at 6.3m/m pace and I could hardly manage 300m as I was running way too fast for 100m and messed my breathing up for the rest. Got a better workout tomorrow but will try fit this route in again but carry on running to get a good PR. Can only go up from here. (Unless I get fat again).
100% this confirms to me that it's all mental. Without looking at the time I didn't think I was running that fast!