I don't think we started from nothing, energy is always present and it cannot be created or destroyed. Life is still present because we evolve and adapt to the different forms of energy we are presented with. I think of time as a gear inside of a clock that turns with other gears like energy and as time being a gear (or in two dimensional form, a cirlce) it is infinite but it repeats. and as time and energy turn it creates what is known as evolution, which brings us to the big bang. The big bang is nothing but a reaction of energy that was created from something that was already present.