You do not want to try and go from zero to sixty right off the bat
. This approach will leave you mentally tired as well as physically tired. You will not be able to find the motivation you need to get out and run on a consistent basis. Consistency is the key to long-term success. It does not do you any good to go out and run really hard for one day, and then do nothing the rest of the week. It is much better for you to get out and run steadily for several days in a row. You will start to see your body progress and this will motivate you each and every day. This approach will help you to enjoy running because you will not be feeling like you are putting pressure on yourself to run really hard. Simply getting out the door is the hardest and most important step to getting in shape as fast as possible.