First time large dog owner after small lap dogs

I’m looking for a dog breed that is larger. I had a border collie mix and a german shepherd as a child. But I’ve only had Cavalier king Charles spaniels as a teen and as I have gotten older.

I love cavs and their cuteness, cuddles and companionship but they have all but one been little couch potatoes. They have all also been sick in some shape or form. From mega esophagus to heart problems. They are just higher risk dogs for numerous conditions.

I’m going to adopt and search for a dog based on behaviour.

QUESTION: What is a larger breed of dog that typically is more active and has fewer health conditions?

I’ve never not had a dog and I can feel the absence.

I want to make it clear that if any dog I get in the future gets a condition or sickness I will always go the distance to support them and give them the best life. However my heart hurts and I would like to take my dog for a walk without the active worry of their heart giving out.

There is so much more research to do before I start applying for adoption. I’m just looking for a place to start.

Thanks 😊