johndoh, to add to shortbread’s and surfer’s posts. I don’t think in min/m anymore so I’ll go with min/km. I think, injury aside, you can get from 24.30 to <24 easily enough. You’re looking at knocking 6s/km off so run intervals at 4.30-4.40/km. Obviously helps if you have a GPS watch to help with this.
Warm-up for 5-7 min.
Run 500m at 4.30-4.40.
Recover for 2-3min. Recovery might be walk for 30s then jog.
Repeat 5-6 times.
Cool down to home.
Do this twice a week. Mornings after a strong coffee are good. I go out twice a week at 0515 with my training partners. If you can find another victim to accompany you, it helps. Also this time of year, it’s lovely running that early. Nice and light, dead roads, generally crisp conditions. It’s only a half hour work out. Run Parkrun on Saturday morning. Aim to go at a constant pace over your 5km – really important to warm up before starting. Gets the heart rate up and you won’t be dying on your arse after what will feel like a fast first km. Willing to bet you’ll go sub-24 after a couple of weeks.
EDIT: If you don’t have a Garmin into which to program an interval session, there are plenty of apps that’ll do it via Bluetooth headphones.