Every morning, as soon as he woke up, Tony would go down to the gym and run. He didn't like running in the streets because he quite often got lost and then had to get JARVIS to guide him home and he always felt a little like an idiot. If there was one thing that Tony disliked more than anything else, it was feeling like an idiot. But, that was why he had spent so much money on such high tech gym equipment. So he could have a place to run right there at home.
As soon as he opened the door he recognized the sounds that were coming from the gym. Heard the pounding of fists on the punching bag. The occasional grunt in a female voice. He decided to just ignore it. Someone needed to work out and didn't want him to bother them, obviously. When he saw who it was, though, he couldn't help but walk over and steady the bag for her. He didn't say a word, just held the bag and braced himself for the onslaught that he knew would come.
If everything his dad told him could be believed, Peggy Carter was a lot stronger than she looked, and she didn't take anything from anybody. Of course he'd found out that second part on his own. So he just made a very brief eye contact and tried to help her get the most out of her workout. The bag swinging free tended to not offer the right amount of resistance to the punches. He'd learned that from Happy.