Some of us are specimens of incredible fitness while others are morbidly obese. Most of us fall somewhere in between. How we feel about being fit says a lot about our character. Is exercising an obsession or a supplement to good health? Does limiting the size of meals mean you are a picky eater or trying to keep off the pounds? On the same note, gorging to excess is also an influential factor in overall fitness.
Your character’s attitude toward physical fitness might not play a key part in the story, but it does tell a reader something about who he is. Imagine him walking through a door into a crowded lob filled with strangers. What do the people see and think when they see him? How do they react? How does he present himself in terms of clothing, ability to walk and overall demeanor?
First appearances often affect future relationships. You need to take this into account in the story. When a dazzling blond model struts into the scene, she receives a different reaction than when a morbidly obese man waddles into the room.
Fill your scene with dialogue, perhaps between casual observers. Narrative is required.
Have fun with this one.