I always hear this same situation. I train people, I'm a personal trainer.
Here's a thought.
People are afraid to go to the gym because of how they look and perform.
Same thing applies to you and airsoft.
The difference is you get off your ass and go to the gym. They can laugh all they want, you gotta start somewhere.
Look at how many people out there that want to play Airsoft but can't because of costs and age.
If you have the option, then do it. Airsoft is intense, you'll sweat off calories and fat like no tomorrow, even standing in one spot.