Hey there! As someone who's made this transition myself, I totally get where you're coming from. Moving from ladder logic to structured text is like switching from driving a manual transmission to an automatic - you're still driving, but the mental model is completely different.

Here are the key mental models that need rewiring:

1. From visual flow to procedural thinking: In ladder logic, you see the electrical flow visually. With structured text, you need to think in terms of procedures, variables, and execution order. It's like going from reading a circuit diagram to writing a recipe.

2. From rungs to statements: Instead of thinking in terms of rungs that execute simultaneously, you're now dealing with sequential statements that execute line by line. This requires much more attention to execution order.

3. From contacts/coils to variables: You're no longer dealing with physical contacts and coils - you're manipulating variables and data structures. This abstraction can be challenging at first.

Now, the old habits that die hardest:

1. The visual debugging crutch: In ladder logic, you can literally see power flowing through rungs. With structured text, you need to rely on variable states and debugging tools. This loss of visual feedback is probably the hardest adjustment.

2. Parallel execution mindset: Ladder logic rungs execute in parallel, while structured text executes sequentially. Breaking the habit of assuming everything happens simultaneously takes time.

3. Over-reliance on ladder-specific patterns: Things like seal-in circuits, one-shots, and timer/counter patterns that are natural in ladder logic need to be rethought in structured text.

4. The comfort of familiarity: Many engineers stick with ladder logic because it's what they know and what's widely accepted in industry. The resistance to change is real!

The good news? Once you make the mental shift, you'll discover that structured text offers incredible power for complex logic, data handling, and code organization. It's definitely worth the learning curve!