Devote your entire life to physical exercise, then join the army (not american) and work your way up through the ranks until you have the highest authority. Next you must create propaganda about the government and lead your entire army in a coup d'état, hold the entire senate and 10,000 civilians hostage and demand that they pass a bill to make the country a military based and controlled country.
Now that they have done that you officially just became a nation leader and have the power to name yourself Führer.
Have fun.