“I don’t think I can.”
Who is the “I” who is doing the thinking and who is the “I” who is wanting to do the thing?
They are not the same entity.
One is ego, and one is your true self.
Remove the ego and you get, “I can.”
[The ideas in this post originates with teachings from Eckhart Tolle, spiritual teacher and author of many pivotal books including A New Earth, which saved me from myself in 2012.]