H PAUL

You need to do both interval training, hill training and some resistance training work.

Interval training: I would suggest you train short intervals i.e 100, 200 or 400m repeats - the shorter the distance- obviously the harder you can push the interval.

Eg 100m - you might start off with just about 6 repeats but slowly build up to at least 10.
The 400m, you could start off with about 3, and gradually build up to about 6 or 7.

Allow sufficient time to recover between repetitions, so that you can maintain your pace throughout the intervals.
Hill training is also an excellent way to become stronger. Again start off with shortish hills and perhaps just run hard up the hill for 30 secs initially - jog down slowly , recover and then repeat, trying to keep up the pace. Perhaps initially you do just 3 repeats - but gradually build up the time to 60 secs and the repeast to at least 6.

Finally, get into the gym and concentrate on some effective resistance training. Illustrated examples of many exercises can be found in the "War on Wobbles" gym programme on the home-page.

Good luck!