When you first start running, chances are your body won't perform as you expect. That's because beginner runners often forget that their bodies need to adjust to the newly introduced strain and stress of running.
As such, a lot of novice runners go all out right from the start, running/jogging too fast. Unfortunately, within only a few minutes, they feel the cost of this mistake in the form of frustration, pain, overexertion, or even injuries.
This is why you must start running at a comfortable pace. You don't have to challenge yourself too much right away, just keep a moderate, conversational speed where you can speak in full sentences. Otherwise, slow down until you can.
Remember to take your breath through the nose and mouth to help your body receive as much oxygen as possible. You can also try deep belly breathing to minimize side cramps or stitches.
Don't forget to cool down your muscles after each run by some laidback jogging or walking. Gentle stretching can also prevent suffering from tight muscles.
Finally, your priority in your new running habit should be doing it consistently, not quickly or for a long distance. This way, you can stick to it first, and the rest will come later.