The amazing thing about technology, as pointed out by Justin Rosenstein, is that it "empowers small groups of passionate people with an astonishing degree of leverage". Quite true. One often sees comments on HN by founders trying to lower their user-to-employee ratio below, say, 10 million. Wait, what? That's, uh, 3% of the United States. You're saying your start-up could serve the entire United States with fewer people than are in the senate. That's, um, wow.
The interesting thing about that degree of leverage is that, from the operating end of the lever, it's often hard to see exactly what's doing on. If you actually had that sort of physical leverage, the natural tremors in your hand would end up knocking buildings down. Fortunately, building software is slightly less dangerous (usually), but the fact remains that the law of unintended consequences can be quite strong. In particular, if one starts with a large goal, calculating the minute operating motions required to achieve it may be next to impossible. The problem is made worse by the fact that the things computers are naturally good at do not necessarily correspond to the things we may want to do in the real world. Sure, we can, with effort, devise various algorithms to improve the correspondence, but at the cost of leverage - and the remaining mismatch between what the algorithm actually accomplishes and what people expect can be quite problematic.
Most of the greatest single innovations in technology have occurred not because somebody set out to accomplish X and didn't stop until they were done, but because either somebody noticed that X happened to be extraordinarily easy to do and found a way (sometimes accidentally) to make it useful, or because somebody noticed that X was already being done with technology, but badly, and put the effort in to make it cheaper or faster or more reliable, without really changing the original insight.
Of course, most things we would point to as 'great' are not single innovations - they are heaps of innovations, each built on top of the others. Amalgamations of ideas and techniques, most thoroughly unimpressive from a technical perspective, which when taken as a whole, manage to seem amazing. But these are not built by any one person, or one group of people - they are, with remarkably few exceptions, accumulated slowly, almost by accident, over time.
What makes an engineer - or a scientist, or mathematician, or anyone else whose job entails building on the works of others, to someday be built one oneself - able to keep slowly hacking at a seemingly inconsequential part of a larger problem is the understanding that it is part of a larger problem, even if not every bit of progress made seems consequential. So keep slowly hacking. Keep doing little things, and doing them well. Each successful step moves us one little bit into the future.
Do small things. Time, technology, and those slaves of yours known as "future generations" will make them great for you.