Getting strong and fit is really, really simple
The fitness community and training in general has gotten completely out of hand. Enter any gym and you'll see the weirdest excercises, often performed by well-conditioned people. Bosu ball one legged bicep curls, all manner of weird glute exercises, backwards walking squats on the freemotion machine. Its a circus out there folks.
I'm here to dump a piece of information that's probably going to make you very happy. Because its simpler. It makes you stronger in less time. It increases bone density, staves off type 2 diabetes, and increases cardiovascular health.
I'm talking about squats, deadlifts and presses.
These are the "old school" exercises that get people massive backs, legs and shoulders. Most professional bodybuilders, I mean the real freaks of nature, do lots of squats, deadlifts and presses. They do this to pack on enormous amounts of muscle because these exercises stimulate more muscle groups, as in all muscle groups, and so cause massive amounts of testosterone and growth factors to be released. And that is what sheds bodyfat and seriously tones muscles.
So here's just a few good points about why these three variations are so effective and, believe it or not, safer than most others.
1) They teach muscle groups to work together, as they are meant to be trained, instead of working in isolation, which is not physiologically normal. The human body is designed to be trained as a group, not piece by piece.
2) They have unexpected benefits that are hard to come by elsewhere. Do you want to build huge grip strength? Quit doing wrist curls with 15 lb dumbbells, and starting pulling 400 lbs off the floor with your bare hands. Personally, my grip strength from deadlifts has gotten to a point where I do not need straps, just some chalk. Also, an exercise like a back squat will strengthen the spine, as will proper deadlifts. And pressing barbells overhead will build up your triceps and even your abs, which have to take the entire load as well.
3) They don't take as long to do. You can get an entire workout in less than 30 minutes if you program in some simple circuits revolving around these big lifts. Try the deadlift / pullup combo and tell me you don't feel like you ran 5 miles afterwards.
4) They build the core better than isolation work. This is a staple in the strength community, which rarely isolates abs. A back squat with 300 lbs requires that your abs and lower back must each also carry 300 lbs. You just can't substitute this type of load with isolation exercises.
5) They are cool. No one is impressed by the guy slinging around 60 lb dumbbell curls. But everyone is impressed when a monster squats 600 lbs ass to grass.
6) They give you something to work on which breeds more commitment to training. Many people seem to get stuck doing the same workouts over and over. When its just isolation stuff there's not a whole lot to work on. By setting a deadlift or squat or press goal, you can really dive into that specific movement and slowly improve. By working on the movement patterns you will naturally learn more about your body and the lift itself. So you actually get better. This is the difference between "training" and just "exercising". One has linear progress, the other does not.
7) All the cool kids are doing it. There's a reason that the only weightlifting sport in the Olympics relies around all three of these movements. A clean and jerk is a complicated version of a deadlift, front squat, and the overhead press. Its literally the pinnacle of lifting. And powerlifting competitions contain only these three lifts. They are the unanimous champions when it comes to increasing strength, muscle size and tone.
One last note that is extremely important:
Yes, these lifts are the best way to go for the most part. But they CAN be dangerous. They are usually only so when someone doesn't properly learn the movement but does it too heavy anyway. We've all been there. Don't let it be you. I learned over a decade how to do these lifts and one reason was that I was getting small injuries a lot at first. I had to learn the movements solidly before I could get to heavier weights. So take the time and preferably higher a trainer that is knowledgeable in these lifts (honestly, most trainers are not, at least not at first).
Now get to squattin'.