Okay, silly question time:

When I was in grad school in VA we would hike in Shenandoah fairly often, frequently waterfall hikes where the return is the uphill part. Not necessarily long hikes, although we did finally do the Old Rag circuit.

Now, I haven't hiked any since August, and I'm out in the Cascades where all the hikes are longer and probably tougher. What's the best way to get back in shape for being able to do longer hikes once the mountains thaw out? (Definitely not up to snuff on outdoor skills to feel comfortable snowshoeing or otherwise putting much time in in higher elevations while it's still snowy yet.) I was thinking of going to the gym and putting in time on a stair machine, but what else?