Less is more! Running harder, faster in hopes of improving performance or endurance is a recipe for injury. Long distance running is a matter of efficiency & energy conservation.
To put it in perspective, running harder for performance is like driving an SUV, you’ll need a lot of fuel but that fuel doesn’t take you very far.
Run like a Prius. (or your fav. Hybrid) Requiring less fuel, hybrids utilize energy stored in breaking when decelerating, and momentum and redirects this energy to running the motor without using as much fuel (efficiency)
Focusing on your core strength, improved hip and ankle (eccentric control) stability and balance, your body will become more adept at utilizing the stored energy, making you an efficient runner.
This has the added bonuses of improving speed, reducing rates of injury and improved recovery.
Run well! Spring is around the corner!