The metal input shaft coming out of the transmission that goes into the neutral safety switch tends to get rusty, which makes it's diameter increase, which binds the plastic of the safety switch, making shifting difficult.
A new neutral safety switch is around $50 (count the number of bolts on your transmission to make sure you get the right one, that's how NAPA classified mine).
Get brutal and pry the old switch off the rusted metal rod, clean up the rust with some light hammer work to return it to its proper diameter, coat the metal rod with anti-seize or some such rust inhibitor, install new switch. Pay attention to the position of the new safety switch versus the position of your shift lever before tightening everything up (ie both in park, etc.)
Shifter now moves like butter!