Cutting firewood. I enjoy all of the above sports but usually can't find the time for them. The one activity I HAVE found the time and motivation for is cutting and splitting firewood to stockpile for winter (I live in central Pennsylvania). There's a saying: "Wood warms you twice -- once when you cut it and then when you burn it." When felling dead trees in the woods and then carrying out the large logs, your leg, back, and core muscles get very strengthened. Later, when splitting the logs with a large maul ax (I use an 8lb head), your shoulders and arms get a huge workout.
I am motivated because I can satisfy several objectives simultaneously:
(1) Getting and maintaining all-around top physical conditioning. (2) Spending hardly any money on heating costs. (3) Interacting directly with nature to better understand and appreciate it.