How to Run a Sub 2 Hour 30
Half Marathon.

For a 2:30 half marathon, focus on building the ability to run for 2.5 hours rather than worrying about speed. Run three times per week: two easy runs of 30–40 minutes and one long run that you gradually extend to 16–18 km.

There's no need for dedicated speed work at this stage — just running consistently will improve your pace naturally. If you want to add variety, include a gentle fartlek in one of your easy runs (pick up the pace slightly for lampposts or 1-minute bursts).

Allow 10–12 weeks and be patient with your long run progression. Increase it by no more than 1–2 km per week. Practice eating and drinking during your long runs — you'll need to fuel during 2.5 hours of running. A gel or energy chew every 45 minutes is a good starting point.