The first time I greased the fittings on my Duramax truck it was a pain. Then I bought a Lumax 90 degree coupler and a new grease gun and it made it a relative snap.
The new grease gun was a Plews pistol grease gun so I could use one hand to hold the right angle fitting in place and the other hand to pump the grease. Well worth the $25 for the pistol grease gun.
I add grease every 3,000 miles and the truck really needs the grease at this mileage mark. No way could it wait for the oil change to be done.