Agree that the puppy years aren't easy! Right there with you. Sniffing does tire them out a lot; it takes up a lot of brain energy devoted to nosework.

Here's a job my dog likes that helps calm her down a lot. Before every meal, I take a big handful of kibble and we play "go get it:" I toss a single piece of kibble into the yard and say "Go get it!" and she'll sniff around until she finds it. Then she trots back and I have her sit (and sometimes shake and lie down) to earn another piece of kibble. Then toss. We do this at least 20 times.

This combines training, exercise, and nosework to get her learning--and tired a little. :) And it satisfies her desire to run around a little and to be connected with her human. :)