1. Gym will get boring soon.
You discover new ways to workout, new machines. Then you set targets - 10 Reps, 15 Reps, 30 Reps and reach them. Then you start getting used to the machines, the reps, the music, the people who come there, the smell. Then you start dragging yourself to Gym. It is like going to office - not fun.
Instead Run - you can create so many variations - Run around a lake, Run inside a Park, Run on a long stretch of road,
Running never gets boring. After every run you get a "Runners High" - you have to experience it to understand it. Its addictive too - a good addiction.
2. You need to wait for your favorite treadmill / machine
When you run you need not wait for anyone - the road is always open.
3. You can enjoy nature.
A hot sun beating on you, your tshirt is wet from your sweat and a cool breeze touches you - and you can feel the heat and coolness penetrating your skin - its a wonderful feeling.
4. You are truly green.
You are burning only your own calories when you run. You are not wasting fossil fuels unnecessarily.
5. No Guilt.
You are not paying for a year's Gym membership and spend the days in guilt when you do not go to the gym. If you don't feel like running - don't run. And when you feel like running - you just take off - wherever in earth you are - on a vacation, on a business trip.
You have a free membership to this gym that is available everywhere - 24x7.
Don't give in to the Gym's pitches - all you need is a cheap shoe and a good headphone - and just run.
A Runner for the rest of my life.