Being a sustainabilitarian is a bit like being that tree. The ravages of the weather are similar to the constant battering we get from many quarters, and indeed from the mainstream of society. You people are just idealist dreamers with no understanding of the real world and how it works", or "You want to take us back to the stone age", or "Economic growth and jobs come first", or "It's too expensive being green", or "It's too late anyway so let's not bother". These are some typical positions in response to the sustainability agenda.
But, like the old oak tree, if we can find a place where our roots can flourish, we can absorb all the hardships and the battering and be steady - steady in the knowledge that we are doing the right thing, that we are building a better future. Sometimes, we just have to endure when times are rough. Ride out the bad times and wait until conditions are more favourable when people will be more receptive to sustainability in the mainstream.
And there's no harm in playing the long game. Many aspects of sustainability involve the long-term - the carbon cycle and the water cycle are just two examples. We don't have to stop carbon emissions tomorrow - we have to stop them in a few decades time. Until then, we have to let the mainstream live well, and carry on the transition to a carbon-free future. If we lead by example, and show how we ourselves can live well on a lower-carbon basis, others will eventually follow.