My road to Rio

torchie, that's a hell of a progression there. all depends how you define "seriously" I guess.

If 20miles a week is the definition, you'll improve simply by upping it with 10 easy miles a week.

If you mean you've been doing 60miles a week, with pace zones, tempo, speedwork etc, it'll take more thought

at your age, with keeness it's all about consistency and avoiding those injuries...which hopefully yours is only a niggle...

torchie, bear in mind that the most dramatic improvements occur during the first few months of your running career. I also started training at my local club at 17 but your improvements will taper off and actually that's when you need the expert coaching (I assume your coach is a qualified one?). So to put it simplistically, don't blame the coach that you haven't continued knocking minutes at a time off your 10k pb.

Good luck! I'd encourage you to try some xc this winter if you hadn't thought of it, it will build your strength and stop you getting too stale chasing road pbs on an all year round basis.