In motor vehicles that burn fuel, there is something called the exhaust pipe which takes the gasses produced by the burnt fuel away from the engine to a point where it is expelled from the vehicle. Exhaust fumes can be quite dangerous to the occupants of the vehicle and that is why it is carefully guided away so it does not harm them.
The gasses produced are a result of the fuel being burnt to create energy that will propel the vehicle in the direction it needs to go. When the vehicle is full of fuel and moving as it should, the exhaust is never a problem.
We however experience two problems with vehicles. One is when we run out of fuel and thus produce no more power to move. The second is when the vehicle has fuel, the engine is running but it makes no movement.
Having no fuel to run our day to day lives produces a type of exhaustion that makes every activity much more difficult than it should be, just like a car without fuel will not move you, but you will need to push it yourself to get anywhere. This is tiring, but wisdom dictates that we find the right things that fuel us to keep going.
The second is having enough fuel but producing no results. The only time we are allowed to be low in results are in a time of rest. It then becomes important that if we are resting, then we must switch off from activities that demand we produce. Just like a car keeps producing exhaust fumes when it is on and not moving and has a higher likelihood to harm occupants who stay in it for long enough, so it is when we do not properly switch off to rest. It creates exhaustion that could harm us.
In summary, get the right fuel that keeps you motivated and going on strong to produce positive results in your life. Also, switch off from all activities requiring your attention when you are taking a rest, this will prevent exhaustion from seeing in and causing you harm.