Every complex system is a combination of several units. Even the most complicated machine has several functional parts which makes it up, and the largest organization in the world is a conglomerate of several departments, divisions, sub-divisions and more.
This tells me that no issue is too large to be tackled, and no dream is too great to be achieved. They can all be broken down to the smallest point of action, from where the journey will begin.
Don’t excuse your dreams by saying it’s too big for you now, and stop procrastinating, thinking a time will come when it will all happen at once. Rome was not built in a day. Start something, start right where you are, and start now. The journey of a thousand miles begins with just one step, and with one more step each time, it will be completed.