How do you actually tire out a high-energy dog without exhausting yourself?

Otto is four years old, working line, and I swear the Spaziergang does basically nothing for him. We do an hour in the morning, sometimes more. He comes home, drinks water, and then stares at me like we never left. I am not a young man and I cannot simply outrun this Hund indefinitely.

I have tried fetch until my arm hurt. I have tried the flirt pole. Mental work (obedience, nose work) does help more than pure physical exercise, honestly, but even then he recovers faster than I do.

I know the standard advice: a tired dog is a good dog, give him a job, structured activity beats free running. I believe all of that. But in practice, day to day, what are people actually doing that works? Especially those of you with high-drive breeds who do not have unlimited time or a large property. What has genuinely made a difference for your dog?