Switching gears and remembering my work-outs for high school wrestling... 
No weights, no machines but a lot of intense calisthenics.  Push-ups, sit-ups, running in place et al in rapid order, then repeat over and over again.  When we ran it was up and down stairs.  Your body is a weight.
_________________________
Better is the Enemy of Good Enough.  
Okay, what’s your point??