It tells them you are not lazy, and most men find such women very exciting.
This shoot was something quite different for me, as I was naked for most of the day! Being comfortable in your pants also indicates that you have no nerve, fear or anxiety about the pants hugging your body, which can further ignite their interests.
The durability of the fabric must also be considered.
If you need the pants for the gym, then you should consider breath-ability and comfort offered by the pants.