Seneca writes that his works are going to last throughout the ages. He even states that he has the ability to take others with him in his legacy. There may not be a lot known about the life of Lucilius, but his name has lived on through the letters addressed to him by Seneca. You have to be rather confident to believe your works will have that kind of lasting power. By the way, Seneca lived in the first century of the Common Era and his works are still being read to this day.
What will your legacy be? Will the work you do impact future generations? If you are only living for yourself, your scope of influence will not be very large. But if you are reaching out and offering the world your talents and skills, you may just find your name lasting through the ages.
The deep flood of time will roll over us; some few great men will raise their heads above it, and, destined at the last to depart into the same realms of silence, will battle against oblivion and maintain their ground for long. –Seneca, Letter XXI. On the Renown Which My Writings Will Bring You