There are a lot of body weight exercises that you could be doing RIGHT NOW all of which would be a step in the right direction, a solid workout could be built around :
Press ups, start with standard and build up through : decline,paused,weighted and ultimately 1 arm.
Dips : in between 2 chairs ,again can be progressed ie weight in lap eg books.
Pullups/chin ups : ok you might need a pull up bar but there is often stuff that you can pull up onto--my example is that i set a simple pull up bar between 2 trees !!.
Squats..body weight at first and then grab something heavy or load up a rucksack and continue !.
Coach Dan john says this :
Pick weight up off the ground
Put weight overhead
Carry weight around.
Nowhere does he say that it has to be posh training kit, as our man above says weight can be buckets of water, ditto jerrycans, rocks ..literally anything laying around.