Often on one of our walking routes, Alice and I see a dog in the yard. He's curious and sometimes barks while wagging his tail. He'll move with us- we on the street and he along the grass. But the dog never leaves the yard. Is there an invisible/electric fence? Is he well-trained? Could he not be bothered?
Did you ever hear of The Baby Elephant Principle? Basically, it’s the idea that an immature elephant--tied to a stake while growing up--will think that it can’t move even when there is no longer a stake or rope present.
Similarly, there was an experiment done in the last century whereby pike fish living in a tank were separated from minnows by a glass plate. After a while, the pike had bumped into the glass partition so often that they stopped going after the minnows, even after the partition was removed.
Are you stuck in the "same ol' same ol'" thinking? What are the (in)visible ropes or partitions that keep you from taking the next step? Let me ask another question: do you know what your "next step" is?
An exercise regimen
A (new) job
Cleaning up that "oh my God!" room
Talking with your doctor
Beginning--or finishing--that project
If you hold back your true, next step it's like not dealing with what's going on inside. As a friend of mine learned when going through recovery, "When you bury your feelings, they are buried alive." They will, in a sense, haunt you until they find healthy expression in a constructive channel.
So who or what is holding you back? If you think you can or cannot... you are correct.