I previously described the negative reasons people get involved in politics. Cynical Response.
On the positive side, political activists see themselves as serving the public interest. They are involved in causes larger than themselves, in movements that have changed the world. “As life is passion and action, it is required of a person to share the action and passion of the times, at peril of being judged not to have lived.” — Oliver Wendell Holmes Jr (1841-1945), who served as an associate justice on the US Supreme Court from 1902 to 1932.
They see politics as “an honorable profession” of serving the public, working for causes larger than themselves, for peaceful change, social justice, serving or embracing the “beloved community” and “the common good,” giving voice to the voiceless.
“Each time a man stands up for an ideal, or acts to improve the lot of others, or strikes out against injustice, he sends forth a tiny ripple of hope, and crossing each other from a million different centers of energy and daring those ripples build a current which can sweep down the mightiest walls of oppression and resistance.” — Robert F. Kennedy, Capetown, South Africa, 1966, encouraging the non-violent anti-apartheid movement, in which a minority of whites ruled over the majority black population. Despite all predictions of a violent cataclysm or long civil war in South Africa, there was a peaceful transition of power in the country, and ultimately, black-majority rule.