As we increase our running mileage, it's natural that we feel the strain a bit more on the body. It's up to you to look after your body. There are a few simple things you can try to help take the pressure off the body after your run.

Stretches
Be sure to cool down and stretch after each of your runs. Work out where you are tight, and build in stretches into the end of your run. Get into a routine of stretching the areas where you know you are tight and hold each stretch for up to 30 seconds.

Sports massage
Treat yourself to a massage by a recommended professional. It's not exactly relaxing, though; a sports-massage professional will loosen out tight muscles by applying pressure to the tight areas and will be able to tell you the areas you need to strengthen and stretch.

Leg drains
Lie on the ground with your legs in the air against a wall. Stay for about 10 minutes or so and notice how fresh your legs feel when you stand up again.

Baths
Try out a nice hot relaxing bath before you go to bed. Some people find Epsom salts very good for the muscles. I won't suggest you try a cold bath if you are training for 5k and 10k runs: they are fantastic for recovery, and I do this myself: but only after very long-distance runs.

Tennis balls and foam rollers
You can loosen out tight areas by applying pressure to them with either a tennis ball or a foam roller. I find the tennis ball great for my feet, and the foam roller very good for the outsides of my legs.

Be sensible
Get plenty of rest and eat good food. Eat well and get to bed early. Nice and simple, and surprisingly effective.