Finding a real solution isn't easy. But solutions are there, and can let you get much more done, more often, more effectively, with better results.
Let's assume you want a combination (you choose the emphasis) of strength gain, leanness, and cardio gains.
It's best to base a workout on compound exercises, which use multiple joints. They get it done thoroughly, in a way that fits naturally how you live and function. (There's plenty more you can add for variety, balance, agility, and looks - more on that later)
Things like a medicine ball, rubber bands and a treadmill won't do much. They miss the important things. And a treadmill, while giving some cardio benefit, will do little else but make saggy bits saggier. (Being steady-state, a cardio device will get less and less effective as your body adjusts)
You benefit best from all angles of presses, pushes, pulls, rowing movements, and heavy leg action. It's properly done with a rack and barbell and weights, or dumbbells and a bench, or a machine that offers equivalent quality and variety. And you don't need a beefy powerlifting style.
Do it with circuits. Do three sets of ten repetitions of an exercise. Rest briefly. Change the exercise, do three sets. Two-three more changes like this...that's a circuit. Do three circuits. That's a workout. Paced achievement, and you feel it and appreciate it, and can soon be creative with it. Increase rest length, reduce reps, increase resistance, and grow strength. Lessen resistance, increase reps, shorten rests, move more towards cardio gain. What ever happens, you'll be stronger, leaner, and improve health and life quality (assuming you have some control over what you eat)(and drink) And the ever-changing pace of strength-centred circuits ensures your body doesn't get used to slacking off.
We have a lot of information on circuits (more here) and both we and the web have a load on training. But let's look at a Leverage Gym, which is special in what it does. (It's an original strength machine for the home and smaller professional gyms, of the most successful family,and with large numbers sold locally)
The Powertec Leverage Gym - that's it in the picture - has been steadily improved over the past 15 years to handle a huge range of heavy-duty and functional exercises using weights on a big lever. Little comes close to handling so much action in a compact space. It offers safety against dropping a weight on one's sensitive bits (has a large, movable steel pin) and wide grip and body size variety. The lever mechanism guides you, letting you concentrate on the lift itself, rather than controlling it. There's a cable set up that offers rows and pull-downs, as well as other compound and isolation (single-muscle) exercises. The bench, which has wheels, moves easily out of the way so you can do squats and dead lifts with the press arms, in standing position. It's good for users up to 188 cm. (Some bigger people like it)
In real terms, you'll get access to more exercises and capability than you'll get in a regular gym unless you're there in a quiet time. Just on the Leverage Gym. You can use it more often, with major time savings and convenience. Add body weight and other types of exercises you enjoy, for balance and agility challenges, for instance. Mix it up with your regular other exercise, such as sport, running, walking - but there is nothing as sound as this kit, for a solid platform if you want fitness' widest range of benefits.
As we said, it's compact. It takes up much less space than the other major tool for strength-oriented training - a power rack. The rack needs a 7 foot 2 inch Olympic bar, so you need well over ten feet overall width to your set up to put plates on and off. The Leverage Gym has plate holders offset and a short distance behind the bar. You can do it comfortably in under 9 feet. Depth i e front-to-back -is similar to a rack's. And the Leverage Gym offers much more exercise variety, with the cable system.
Here's the Leverage Gym in detail.