If you don't have access to weights or a gym that's no excuse for not getting fitter and stronger...
Squats too easy? Do one-legged squats. If that's too easy do one-legged jumps.
Get out and find some scaffolding or a park with a climing frame and do pull-ups. If that's too easy do one-arm pull-ups or wear a rucksack full of something heavy.
If pushups are too easy push yourself explosively off the ground as high as possible with each rep, and do inverted pushups against a wall to exercise those shoulders.
If all else fails just find something heavy like a rock, a sack of gravel or whatever you can lay your hands on to lift and throw.
Many of these routines are actually superior to weights or gym machines in that they tend to give a more holistic body workout, strengthening the core and working multiple muscle groups.