Do not increase your distance more than 3 miles a week

You should not increase your weekly mileage more than 3 miles in any one week. This will ensure that you build up slowly. Jumps in mileage are asking for injury.

 Keep at it for at least 4 weeks

For many runners, the first 3-4 weeks are a real struggle. Every time you put on your running shoes, you wonder why you are doing it. But one day, after about 3 weeks, you will suddenly feel the wind at your back, and you will run easily and smoothly without effort. Running will get easier from then on, and the good days will increase while the hard days recede. Enjoy it: you have become a runner.