James Clear is right all along. After identifying a goal (our desired end state), we should forget about it. The reason is that an end state is beyond our control. What we can control is performing actions and maintaining practices that we know could produce the end state that we want to achieve. It doesn't assure that we get there. So many things can happen along the way. But it gives us a sense of doing something—of trying.

This setting and forgetting is quite connected to the Buddhist and Hindu admonition of non-attachment or doing the best you could without expecting anything. A focus on what you can control (conscious thought and conscious action, which all boils down to "consciousness" of our attention: the only thing you can truly control is your attention) is also a lesson of stoicism. When I look around, I see this being practiced all the time (for example, long-term investing also follows this).

References

Clear, J. (2018). Atomic Habits: An Easy & Proven Way to Build Good Habits & Break Bad Ones (Illustrated edition). Avery.