Hi, Nina Sakura.

Although cycling is my only aerobic sport now, I used to cross-train to supplement my aerobic fitness by running (minimum of an 8-minute mile) three 5 KMs a week. I never ran a marathon (nor did I ever want to do so), so I can’t be of much help there. Nonetheless, for your consideration, here are the practices that I found to be the most beneficial for running:

1) Warm up by slow-jogging at least ¼ of a mile.
2) Stretch thoroughly: legs (calves, quadriceps, glutei, hamstrings), back (latissimus dorci, trapezius, erector spinae), shoulders and neck. Stretching is very important because it helps to avoid injuries.
3) Set yourself a goal of either time (mile per minute, or total time per distance), or distance (how far you run) and force yourself to meet that goal, increasing the goal as necessary.
4) Warm down after the run is over, by either slow-jogging or walking at least ¼ of a mile.
5) Stretch thoroughly again, same as above.

If you aren’t already familiar with how to do so, I also suggest that you learn how to hydrate properly, and how to feed your body what it needs to recover from the stress it endures while running. The proper amount of sleep is important, too.

Of course, it depends on your goals, but if your intent is to systematically increase your fitness level, with a goal of getting stronger, faster, and more competitive, I suggest that you learn about zone training (a percentage of your maximum heart rate) to make the most of your workouts.

Other basic necessities are good, quality running shoes, and functional running attire.

I’m sure there are other, more experienced and dedicated runners here who can give you advice as well.

CMI