Sets an example for others, especially the younger generation. Reinforces that living up to a principle can benefit everyone. Puts ethics above selfishness, greed, hate.
Humans change their behavior based on what they see other humans doing. A person seeing most people or people of influence acting primarily in self-interest makes them that person more likely to do the same.
And, no, Libertarians, everyone acting in self-interest does not lead to better outcomes. That’s a childless myth.
Don’t over think it. You’re going for a walk and the other person is going on the same walk. Talk about your experience on the walk, ask about theirs. Let conversation happen.
If you’re going to be attracted to this person, you’ll know.
It’s possible that you’re just asexual like 1 out of every 100 people. It’s possible that there are circumstances of your past that contribute to this and your social anxiety. A therapist should be able to help sort that out.