Is it possible for one to take it upon themselves to fulfill the requirements of the Mashiach?

A Jew is obligated to keep the Mitzvot. Encouraging and absorbing Aliyah, building Jerusalem and settling the entire Land of Israel are goals that are incumbent on all Jews- not just the Mashiach- as part of Mitzvat Yishuv Eretz Yisrael. Each person should contribute his maximum to the achievement of these goals. One should be careful not to fall prey to delusions of grandeur. Instead, put an emphasis on doing good.