This is a quick tip to help you to prevent injury and improve your running.
Get hold of a piece of 2 x 4 or something similar, about a foot long, and leave it on the floor near to a doorway. I have mine by the kitchen door.
Then every time you go through the doorway you can put the ball of one foot on it and raise your heel from the floor as high as you can. You can use the door frame to steady yourself.
Depending on how strong you are, you may have to start using both feet until you are strong enough to to do one leg at a time. Also you may not be able to stretch your heel to the floor with your foot so high, but this does not matter.
Do not overstretch!
Similarly you may have to start doing five or six reps and build up to about fifteen.
Aim to do three sets of fifteen.
Then you can do more reps or sets or carry some weight if you feel the need to do more.
This is an Achilles tendon rehabilitation exercise, so it will help strengthen your tendons and your calf muscles.
Increased ankle strength will reduce your chances of injury and, if you are running properly, will result in faster running