Low impact activities for senior dogs!

I have a large senior dog who is just the sweetest most absolute angel of a dog but she is unfortunately starting to slow down a bit in terms of exercise and what she can and can’t do. I’ve noticed lately she seems a bit bored as it’s been quite hot where I am and she is double coated so we try to minimize time outside when it’s that hot. If she had her way she’d lay on the lawn all day long no matter how hot. We already have multiple puzzles and lots of toys for her, she is very food motivated and loves to learn. She’s also a big fan of water but she’s not a big swimmer but she does have a pool for the summer to cool off in. What are some other activities or games I can incorporate into her day to help her feel less bored? She can go for short walks a few times a week too but can be hard to do so if it’s quite hot. Thank you in advance!!