Time is relative, we're just stuck in an instance.

     For those of you saying that time "isn't real"... well, it is real. It's just relative. Time is relative like nearly all things are. For example, a year on Mars is longer than an Earth year, but that doesn't mean that when I'm on Mars I literally age slower, it just means the time on Mars is different relative to time on Earth. I could be born on Mars and live to 40 Mars' years old (which is about 75 Earth years) so if I were to travel to Earth, even though I'm only 40 Mars' years old, I would be 75.287671 Earth years old, and thus look like an old man.

Relativity can be confusing if it's a concept you don't understand. Imagine this: a spacecraft that can travel 99.999...% the speed of light. As we know (with experiments conducted on Earth, time dilation exists. Which means, the faster you are moving, the slower time moves for you. Also, as far as we know, the speed of light is the "speed limit" of the universe. So, a ship travelling 99.999....% the speed of light would experience such time dilation that, relative to those on Earth, it would seems as if the person didn't age at all. Here's a scenario, two twins both 20 years old. One is an astronaut and gets of our ship travelling damn close to the speed of light to a star 1 light year away. He doesn't stay there though, he just travels 1 light years there, then 1 light year back without stopping. So for the astronaut and the spaceship, 2 years have passed.  However, on Earth, his twin may have aged 40 years, but remember, these are Earth years. The time dilation have caused the twins to age (relatively) at a much different rate, however, they have aged at the same rate (relative to where they are/were). 

Imagine this, if Earth started going around the Sun twice as fast, people would suddenly "age" faster. However, it would only be relative to Earth. An instance of time such as "year" should also come with a specification of location so that the relativity can be taken into account, "1 Earth year" or "1 Mars year" (with the Mars' year being twice as long.   
    
So, time is relative. We are perpetually stuck in one instance of time (for example, I can only see you as you are right now, this moment, not as you were 5 mins or years ago), although, we can observe "time" moving, life grows and dies, stars grow and die, just because we don't have the power to see time in its entirety (the 4th dimension), doesn't mean it doesn't exist. Just like it doesn't mean that depth doesn't exist even if we were only able to see length and width (2nd dimension). Imagine walking through the 2nd dimension, if there were "beings" in that dimension, they would only be able to see one plane of you (like a ct scan as it goes through your body), just like we are only able to see one plane of time as we pass through it (only able to see this single moment as it passes). Get it?