That's what makes a photographer happy.
Yes, it is good to have a good camera, with a charged battery and large capacity for high quality photographs. But planned photographs can give you only so much satisfaction.
Serendipity gives you the extra.
While traveling East along the shore of the Rouge River of Southwestern Oregon, I looked up at the right time from the right place and caught a glimpse of an eagle's nest. So I stopped and moved until there was just the right angle for a clean photo of it.