Properly Attach Cabling To Joists
There are staplers meant for wiring that are great for situations where you don't have too much room for a screwdriver or to swing a hammer. The Arrow T25 is one model, but there are other options out there.

Just do a search for Cat5 stapler and you should find lot of options. Make sure you pay attention to the instructions and use the right staples or else you could accidentally cut one or more of the conductors in your cable.

Another method is to staple a zip tie to the joist and then fasten it around the Cat5.