Find purpose which aligns with "progress or wellbeing of our species". Making kids is one, making inventions is another, helping poor or sweeping roads fits too. If you see that your "way of living" will affect people positively, typically you will have a "good life purpose".

What happens when you have kids? You leave something that will last after your death. Then you make sure that they are properly raised and have enough resources, so that your "mark on the world" is more appreciated by other people. Ultimately all the "good life" have one thing in common. Improving life of our species.

I understand this is childish, but nobody asked me if I wanted to be on this rock hurling through space at 230K/s. Thanks, parents :)