I have recently started adding hiking as my complement to weight training (I used to run), as there is a decent wooded path near my house. A recent enhancement to this steady state cardio was a weighted backpack. It is low tech: about 25 pounds of old cement barbell weights in a beat-up backpack. It doesn’t seem like much at first, but it really starts to make you work on elevation changes.
Speaking of elevation changes, I recently tried using a GPS app on my phone that allows me to save a KML file (GPS coordinates over time) that can be imported into Google Earth. If you’re a runner/walker/hiker you must start using something like this. The detail GEarth shows you is amazing. For example, here’s an elevation/speed graph of a recent hike (I only turned on the GPS half way through):
The cumulative elevation gain is about 320ft, which really makes that backpack start to get heavy. I estimate that my whole path is about 3 miles and probably closer to 1000ft CEG, but I need to run the full path in GPS to check.