At your level in table tennis, fitness might not seem very important.  However, if you want to improve 2-3 levels, fitness will become an important aspect of your game.  Prepare for improvement!  Avoid injuries!  Increase your speed!  Boost your endurance!  At the end of every training session, do 20-30 minutes of intense physical training focusing mainly on foot speed, core strength, stability, and balance.  

Question:    Can I get fit playing ping pong/ table tennis?
 
Answer:        Yes you can.  Here are the stats:
 
Recreation ping pong  - 200 calories/hour
Professional table tennis athlete (moderate drills) – 800 calories/hour
Professional table tennis athlete (highest intensity) – 1000 calories/hour
-Compared to-
Running 7mph – 800 calories