“I can’t because <insert reason or excuse here>.”
This can be a very valid, honest comment. It can also be your false justification for lack of effort and initiative.
This can be a correct answer. It can also be an answer that actually creates problems.
This can be a way to explain a true obstacle. It can also be THE obstacle.
This can be a way to identify the obstacles to overcome. It can also be a personal mantra, repeated all day long, reinforcing that failure is the only option and the excuses are all to blame.
This can be a short-term issue. It can also be a life-time barrier, preventing the effort to succeed.
This can be a message to others. It can also be a message to yourself (and typically a bad message).
This can be communication of facts. It can also be a communication of only selected facts, intent on justifying emotional decisions.
This can be the establishment of a healthy personal boundary. It can also be a destroyer of boundaries, leading to unhealthy relationships.
This can be the motivation to find a way to succeed. It can also be the motivation to never make much effort.
This can be a great direct response to an irrational or improper request. It can also be an irrational or improper response to a great request.
“I can’t” statements are not necessarily good or bad. They can be either, depending on their use. However, my observation is that the more often you hear someone one say “I can’t” (or the more you say it), the more limiting it becomes. It moves from an appropriate valid response to become a dangerous barrier to progress and growth.
Effective communication drives attitude, which in turn drives behavior. What you say and what you hear forms how you see the world and how you interact with that world. Be aware of not only the words but their use and learn to make them your ally for success.