Incorporate a back pack loaded up with some weight. Use can foods, books, rocks, anything you would like. There are multiple exercises you can do with the a weighted back pack. Here are a few. 

Push ups, Squats, Pull Ups, Planks, Overhead press, Overhead tricep extensions, Curls, Lunges, Jumps, and more. 

Incorporate Resistance Bands into your workouts.

Link to different resistance bands exercises -

 Resistance Banded Exercises