Do you really care about what that ant outside your front door thinks or what it’s motivations are?
The purpose of your continued existence is to continue existing.
That’s a fairly heady charge for anyone.
I'm not sure why you keep bringing up ants, but this is a statement about the "why." You have made a statement, which means you consider your answer to have value.
To demonstrate the importance of "why," let me ask you this, is the purpose of your continued existence to continue existing no matter what? Is it, maybe, to continue existing until you don't like it anymore? At such time, are you free to discontinue your own existence?