Planning to make my body fit, is running neccesary to build my endurance?

No: It is one of many activities to do this. Any cardiovascular activity performed at a specifically determined heart rate for a specific duration can help develop this. Rowing, cycling, spinning, swimming and running will all work. Weight training can be added for bone and support component (ligaments, tendons,etc. ) strengthening . (USAT Level I coach). Good Luck.

Combine strength: with cardio. For example jump rope for 3 minutes, followed by squats and push ups. Pyramid intervals start with short bursts of high intensity and then build up. Also if your goal is endurance, reduce your amount of rest.