An interval timer, is a device with two countdown clocks, and a round counter.

The two countdowns represent workout duration and rest duration, and the round represent how many repetitions of the two.

An important function of a clip-on timer, that goes on your belt, is the vibrate mode, that you will feel even when listening to music.

Interval timers are both misunderstood, and sometimes developed for another purpose.

One wristwatch timer I just looked at, for example, had a limit of 10 rounds, making it useless.

The interval timer is part of a combination of tools, and in fact can be eliminated, if you are willing to jog.

Jogging is a natural way to build up your endurance, and adding dumbbells will quickly prepare you for lifting a the gym.

The natural jogger instinct says, it is not a jog until it is straight through the hour, or non-stop.

And the only difference between jogging and fitness or bodybuilding, is you add dumbbells, and increase the weight as your body adapts.

Not everyone wants to begin fitness and bodybuilding with jogging, some people maybe too large, or may hope for instant results

Many will want to avoid the impact jogging will have on their body, and get straight to building big muscle.

Those who have been tricked into lifting heavy for a few seconds, and spend 99% of their stay on the phone, also benefit from a timer.

Simply put, a timer tells you when to lift, and when to rest, and how many times you repeat the cycle of lifting and resting.

Fitness and bodybuilding requires a full body exercise, and that can only mean dumbbells that weight your body down.

Furthermore, cycling standing dumbbell exercises, lets one muscle group rest while you work another, without stopping.

The encompassing system requires music, and focusing on hitting every beat.

Which helps you enter a dance trance, that makes time pass faster.

And ensures, that you are lifting at consistent speeds.

To ensure your body enters the adaption process, that fitness and bodybuilding requires.

You need to start in the beginning of the rack, with the lightest of dumbbells.

During jogging, once you can run through, you start with 3 pounds.

And the rule is, not so light that you can lift more, but not so heavy that you are forced to stop.

With an interval timer, things are a tiny bit more complex.

You also start in the beginning of the rack, and then ask how long can I lift these dumbbells for.

And how long must I rest to reliably do it again, you then set the round counter to fill the hour.

And slowly begin shortening the rest duration, as your body adapts, with the aim of eliminating it completely.

People who have trouble with focus, will get a constant reminder, from the vibrate function, and never sit too long, or lift too heavy.

As they slowly shorten their rest period, they will eventually adapt to workout non-stop.

At which point, they can put the timer away.

The dumbell workout is just cycling Lateral Raise, Standing Curls, and the Overhead Shoulder Press without stopping to rest.

In a few weeks the body will grow muscle and adapt to the challenge, allowing for moving up higher in weight.