Here are 5 things I've tried that have made a serious difference in my long and short runs.
1. Take more steps
I mean this very literally. If you are going from point a to b and your normal stride will get you there in 3 steps, try 4 or 5. Shortening your stride will do a number of things. It will keep you from reaching forward with your lead leg and heal striking. Without citing a bunch of stuff about impact on the calcaneous and skeletal system, basically what this does is make your gait more fluid. Your heel out front means breaking action and that's the last thing you want. Shorter stride also encourages you to land on your mid-foot which reduces impact by putting you on top of your feet instead of behind them.
2. Be as tall as you can
One of the biggest complaints from runners as they increase distance is upper body pain. Some of this is the runner equivalent of computer posture and is often a hunching or tightening-up issue. Stand up, grab your head from both sides and gently pull straight up. Feel the elevation and stretch all the way down your spine and try to keep that elevated sensation when you are running and you'll reduce the amount of work your upper body is doing.
3. Run as quietly as you can
Your feet and calves should be as relaxed as you can make them. Feet slapping or slamming down means impact. Tightening up in the lower leg is a huge waste of energy and will lead to taught muscles that injure easily and recover slowly. One way to help with this is to make your landings as quiet as you possibly can. In order to do this you have to use the muscles of your upper legs to absorb landing shock and keep your impact to a minimum.
4. Think fluid thoughts
Ok, new age alert, all cynics please skip ahead. I would say the most common problem I came across as a trainer was people who spent their entire workout or run thinking about how hard everything is. Just like the smile and smile some more tip from yesterday, if you're thinking words like: fluid, gentle, and graceful you will be those things. The harder your thoughts the harder your life will be. Give yourself a break and make things easier. Tell yourself you love running and it is fluid and joyful. It helps a lot even if you don't believe it at first. You get to have a self fulfilling prophecy you'll appreciate.
5. Say hello to everyone you pass
Be the nicest person on the street and make other people smile. That really will make your run a pleasure. Make a habit of saying hello to everyone you pass and I swear they will magically fuel you with their surprise and delight. I'm telling you, the nicer you are the better you will feel and the more fun your run will be. These last two tips are great ways to make anything you do more pleasurable as they give you ways of interrupting debilitating thought patterns.
Hope these help. These are 5 of the many things I try to keep in mind when I set out to run. Whenever I find myself feeling run down, I check back in with my physical form first: move feet faster, get taller, get quieter, then move on to my internal form: think fluid and joyful, friendly up and find someone to smile at.