Push ups are wonderful for building strength in your body. You can always modify them to further challenge your body and target more muscles. The PUM can help with that. It is a push up machine with 0%, 5%, and 10% settings to your chest, core, and shoulders muscles.
The PUM aligns your body in the proper position and has 3 touch points to keep you honest. It has a fairly compact design, so you can take it anywhere.