Once you've consistently worked on as many animals as possible it's time to step it up a notch. Make a game out of the animals you have learned and use these games to attack goals and create challenges that are interesting and give you great benefit. The animal dice game is my most personal favorite and for good reason.
It goes beyond just doing random animals per round; it teaches you how to get ready for whatever comes next because like life it's unpredictable and certain things can happen when you least expect it. It teaches you to expect the unexpected and when you can go round after round it takes on a life of its own. The playout is never the same twice so you're on constant alert.
Conditioning both your mind and body gives you an idea of where things can go and you can keep going even when you're ready to quit. You can be just as strong even towards the end but you still never know what can come up. I have literally done hundreds, thousands of rounds with this game and done hundreds of reps total each time and it never gets easier; only more interesting. There can be times where most rounds are upper body others can be lower but again you're on constant alert and you must be prepared to do that animal. You can make up any animal you want with the dice and you can switch things up on a fly if you wish but never mistake that it is a cake walk. It literally forces you to adapt and having to improvise some rounds just to keep things going. One game can teach you many things beyond the numbers and the types of animals; it enhances memory, conditioning and tells you to always be ready.
To really spice it up, don't always do steps; do yards, meters, feet, inches whatever you choose make it interesting. I like to double sometimes triple the amount of steps per animal to make it challenging and force me to train harder than usual. It's always fun but in the end, I control the challenge but I can't control what animal comes up next. It's a simple game that will turn even some of the most conditioned athletes into the most humble individuals you'll ever witness. Like in sports, anything can happen and a single moment can change the entire outcome of a fight, match, game or whatever; like the game, one animal can bring you down when you least expect or you'll rise up and tackle it with a vengeance either in the first round or 50th.
Get in the habit of moving like an animal and challenge yourself while having fun and taking your conditioning to another realm.