I think it's very important that every dog (senior dog or not) can have a daily opportunity to go out and smell the roses, trees, bushes, every pole in the neighborhood to read the latest peepee news.. even when you have a big garden.
If you don't want a high energy senior dog, check with the shelter where you will rescue him/her. There are at lot of differences.
Grigri is 11 and loves to be lazy (maybe his puppy mill history has something to do with that), but her friend Chika who is a terrier is also 11 is high energy and she LOOOOOOOOVES to walk.. a lot.. you read that right.. LOOOOOOOVES to walk.
Normally I take Grigri on a daily walk to the park (on average a one hour walk), which includes carrying Grigri for at least 15 minutes (which goes like this.. Grigri laying flat on the ground REFUSING to move.. especially when there are a lot of people around who can enjoy his performance) and once at the park he has to sniff EVERY little pole in our park and pee on it to leave a reply.. and there are a lot of it.. not to mention the trees...
Good thing about senior dogs, when they get home they will sleep the rest of the day, dreaming about all the news they left to their friends..
Does your dog walk every day ?
a 'Senior Dog' mom-O-Holic.