To keep enjoying something you need to increase its complexity

I think I get this, but not quite sure.  In the previous paragraph, he talks about trying to get more enjoyment out of mundane activities like brushing your teeth.  I have found if I try to be more precise in mundane activities, it helps to resent them less.  But in the next segment he goes on to say that that

Generally it is more satisfying to become involved in activities that are inexhaustible--music, poetry, carpentry, computers, gardening, philosophy, or deep personal relationships.
Most domains are so complex that they cannot be exhausted in a lifetime, not even the lifetime of the human race...