I have few questions and queries:
1. Is ledPin a symbolic name for DPin-13 or ledPin is a variable to which you are assigning a value of 13?
2. analogRead(); always returns a positive value; there is no scope for it to be negative. If so, why have you declared the variable as int potRead; rather than unsigned int potRead;?
3. You have said that the the LED will become ON when the pot-wiper arrives at its mid-point which is about 1023/2 = 511. You know this value; then, why have you transformed the pot-range ( 0 to 1023) into (0 to 255) using map() function?
4. In the comment you have said that LED is an output. Is it an output line or an output device?
5. Literate Programming Style says that the brace ({) should always be at the new line position and alone. Why have you placed it at the same line of the control structure -- if(potValue >= 125){ ?
We appreciate your courage for facing questions!