The life of a theoretical physicist

Here's an excerpt from "The Trouble with Physics", by Lee Smolin:

"We are talking about thirty years of continual hard work, involving many complicated calculations. Imagine doing your income tax every day, all day, for a week, and still not getting the calculations to add up consistently. You have an error somewhere, but you can't find it. Now imagine a month spent like that. Can you stretch it to a year? Now imagine twenty years. Now imagine that there are a couple of dozen people around the world spending their time like this."

Here's another:

"Supergravity was not doing this (starting from a deep principle). Although it was indeed a proposal for a new unification, it was one that could be expressed, and checked, only in the context of mind-crushingly boring calculations."

These sentiments pretty much summed up the reason why I cannot be a theoretical physicist. I have already been exposed to mind-crushingly boring calculations while doing 6 problems a week from Jackson's "Classical Electrodynamics". They took 20-25 hours every week. There was a Quantum Mechanics class, where the homework sometimes just could not be done. I gave up on those - but I remembered a friend who will persevere to the bitter end. He took extensions and spent a week on one particular problem. And he scared me to death.

If I cannot even tolerate a 25-hour problem set, how can I possibly bring myself to persevere for 20 years? I imagine some of these 20-year people may be as smart as Dirac, Feynmann, or even Einstein, but somehow they were on the wrong track, or borned at the wrong time. If your theory works, you win the nobel prize and achieve immortality. If not, well, your whole life is a tragedy. If Einstein is alive today, would he work on String Theory? Can he bring about another revolution in Physics?

Ultimately, I have deep respect for theoretical physicists. They are in a field that I am dying to go into, but do not have the guts or perseverance for.