A funny fact about the sun is that it is a very slow nuclear reactor. [View all]

[Odin2005]

It's power comes from it's mass, any particular square inch of the Sun's core does not produce enough energy to power a TV, but the sun is huge and all that energy adds up

And that slowness is a good thing, it's why it's been chugging along for 4.6 billion years and will keep chugging for another 5 billion.

To give some perspective, any one proton in the sun's core has only a 50% of being fused into a helium nucleus over the Sun's entire lifetime.

Red dwarfs are even slower, and the whole star is convective, so it has to go through ALL of it's hydrogen before it dies, that will take over a TRILLION years, Proxima Centauri will be burning hydrogen long after the Sun and Alpha Centauri have died.

The great mass of the big blue stars means that they burn very quickly and the most massive like the bright blue stars in the Orion Nebula, live for only a few million years despite weighing up to 130 times more than the Sun.