I think the one and only thing that humans can derive pleasure from is progress. In order to progress, however, one has to continuously expand their limits and

I think the one and only thing that humans can derive pleasure from is progress. In order to progress, however, one has to continuously expand their limits and that is painful. So really (true, sustainable) pleasure and pain come hand in hand. The 'secret' to maximizing happiness is to avoid the pain that doesn't lead to progress.