necessarily about completing something, but about improving my times. For example: did you know you can enter just about any college track and field track meet as an unattached or masters athlete? You could train for a mile, or 800, and enter a track meet in your area.
You could also try going to one the city arts centers and try painting, drawing, cooking, photography, gardening, etc.
Also, for me, I don't think 24/7 about my passions or hobbies. At times I think or daydream about them, but it's mostly just something I enjoy.
Try stuff out, I think you're on the right track!