Fitness, recreation, free mind, endurance and more. All these activities with minimal cost and less involvement with others is possible only in running.
Cost factor: Running involves one time investment which would sustain for some years. There is no need to buy high end shoes for running. A perfect fit which would not bring injuries is enough. There is no recurring cost.
Company: It is not mandatory that you need people around for running. The dependency factor is less. You feel like running just get up put on your shoes and start running. It takes two to tango, atleast 3-4 to play football, cricket, and any other sport but running its just you and the whole world in front of you.
Track & Trail: Where to run? There is no need for playground or open spaces to start running. The road is free. Nobody stops you from running on the road. You can run in nearby parks. If everything is boring then find a track which is off the main roads & has nice scenery. If you stay in coastal region then beach is always there for running watching the sunrise or the sunset.
Mind factor: When you run one can think over lot of things thats going on in the mind. It gives time and independence to think freely. No negative thoughts, just clear mind and clarity.
Endurance: In this world there is lot of negative energy around you. Anything you want to do there will always be a force which will undermine your efforts or push you to give it up. Working against all these, the moment you push yourself and reach the last step there is a smile, satisfaction of completion. The extra mile effort always pays.
Fitness: Everyday run of even a km burns some amount of calories. Brings about a balance in the body.
One can think of anything else as per ones own body and interest. Running is simple, no dependence and its an open world.