We must attend to our practical responsibilities. That is part of being a human being. But there is no inherent pain in fulfilling the natural purposes of this physical life. Pain comes in when we turn a natural purpose into something personal and become identified with a role that we believe we have to keep in place.
When a purpose of ours has run its course, we must be willing to see the need to let it go. If we do not let it go, then we run for nothing. The painful consequence of running for nothing is the constant sense of being incomplete and unfulfilled. We need to see that something in us wants to relive what we have been and done at the cost of our higher possibilities.
As strange as it sounds, our pain actually convinces us that what we are doing is right. Pain seems to prove to us that our invented purposes are for the good and worthwhile. When we attempt to hold onto a purpose that has passed its natural completion, the result is unnecessary pain. As long as we hold on, the pain will increase, not because something is trying to punish us, but because a loving intelligence is actually trying wake us up and wrench what we are clinging to from our psychological hands.