Why are you still going?

In this extremely fast paced world and growing needs, what do you think keeps you going?
It's natural to get tired and weak from the whole hustling, bustling and survival to live, but when you get really tired, what is the boost, what motivates you to want to keep going?

For me i think it's the number of people looking up to me and others waiting for my downfall, it's pretty weird right? Sometimes, i want to give up and end the race but a lot of people are looking up to me and it would be disappointing to leave them hanging whereas there are others that are just waiting to say "i knew she couldn't do it", this kind of people make me want to smash all my goals and say "i knew i could do this".

Enough of me, back to you...what keeps you motivated when you get tired?