Possession for its own sake or in competition with the rest of the neighborhood would have been Thoreau’s idea of the low levels. The active discipline of heightening one’s perception of what is enduring in nature would have been his idea of the high. What he saved from the low was time and effort he could spend on the high. Thoreau certainly disapproved of starvation, but he would put into feeding himself only as much effort as he would keep him functioning for more important efforts.
Effort is the gist of it. There is no happiness except as we take on life-engaging difficulties. Short of the impossible, as Yeats put it, the satisfaction we et from a lifetime depends on how high we choose our difficulties. Robert Frost was thinking in something like the same terms when he spoke of "The pleasure of taking pains". The mortal flaw in the advertised version of happiness is in the fact that it purports to be effortless.
We demand difficulty even in our games. We demand it because without difficulty there can be no game. A game is a way of making something hard for the fun of it. The rules of the game are an arbitrary imposition of difficulty. When someone ruins the fun, he always does so by refusing to play by the rules. It is easier to win if you are free, at your pleasure, to change the wholly arbitrary rules, but the fun is in winning within the rules. No difficulty, no fun.