We have a rottweiler, average energy level, and an English Mastiff, low energy level.
For us, it's pretty simple. I walk them every morning after breakfast, before we head out to go to the beach, sight seeing, hiking, etc.
Seriously, they sleep on my bed the entire time. If I'm gone for 1 hour or 6, they're still asleep on my bed when we return.
I did learn they MUST be exercised first, and I have to close all of my blinds bc my rottie would see us leave and become upset and scratch at the windows. He's fine as long as the blinds are closed and the AC is on. You could also leave the TV on to help block out any outside noises.
Good luck.