Why is it that the drivers door power Window on my 2002 Nissan Sentra needs help to get it up?

More than likely, the window motor and/or regulator, (the mechanical part that raises and lowers the window - which is driven by the motor), is not good. Either, the motor has become weak, and/or the regulator is getting bound up.

The driver's window generally gets used the most, so is likely to fail first.