Hillary Clinton is going to run for president in 2016. Granted, she is exhibiting even more coyness than most presidential prospects, and yes, the media are filled with those asking “Will she or won’t she?” But the only real question is: How could she not run?

How can someone who has spent a life in politics and who sees a clear path to becoming president not run? Mrs. Clinton started her career four decades ago, working with the House Judiciary Committee staff during Watergate. She served as first lady in Arkansas, as an active and highly visible first lady in Washington, as a U.S. senator and as secretary of state. She may have the most diverse political experience of any nominee for president in the last 20 years.

How can a feminist icon not run when she has a solid chance to become the first female president of the United States? Mrs. Clinton surely knows how close she came in 2008. Had she won the Democratic nomination, she would have almost certainly ridden a feminist wave to a victory over John McCain, and she’d likely be in her second term now. She recognizes the election of a female president would mean something for future generations.

Her husband seems to want her to run, and there is no indication their daughter is against it. Eight years will have passed since 2008, and at close to 70, she’d be older than recent nominees other than Mr. McCain. But assuming her health does not deteriorate, she should seem fit for office. She’s certainly tough enough. The 2008 nomination process and her sometimes rocky tenure as first lady would lead one to think there is no new scandal or embarrassment—involving her or her husband—that could come to light between now and 2016 and be large enough to derail a campaign.

It is difficult to think of any possible Democrat opponent who could best Mrs. Clinton for the nomination. A recent poll of likely Democratic voters in the important primary state of New Hampshire shows Mrs. Clinton with 64%, more than four times as much support as the next four names combined. True, it’s doubtful many people saw Barack Obama as a nomination threat in 2005, and it is possible some very strong candidates will emerge between now and 2016. But Mrs. Clinton starts with quite an advantage.

To keep that advantage, she must begin the process of increasing the number of Democrats who are politically indebted to her by campaigning and raising money for the party’s candidates for congress and governor. Her recent stumping on behalf of Terry McAuliffe, who’s running for Virginia governor, is certainly a start.

She needs to evaluate the shortfalls of her 2008 campaign and make sure she corrects them. She needs to start squeezing out any competition; if she lets word get around to liberal donors and party apparatchiks that she’s likely to run, that would suck much of the air out of other potential campaigns. She will need—at the right time and in the right way—to solicit President Obama’s support, or at the very least see that he does not actively support her competition.

While questions from Mr. Clinton’s tenure as governor and president are old news now and will be even older in 2016, Mrs. Clinton and her team will need to develop a response when the Benghazi tragedy, which occurred on her watch at the State Department, inevitably arises on the trail. Fairly or not, it is doubtful she will suffer much in the way of fallout, but when the Benghazi issue does arise, she won’t want it to consume more than one or two news cycles.

To win the general election, she should hope the Republicans nominate a candidate as uninspiring as Mr. McCain. Demographics will play a role. Will the Republicans have a woman on the ticket, or an African-American? Would a Republican nominee like Sen. Ted Cruz or Sen. Marco Rubio pull Hispanic voters from Mrs. Clinton’s column? Or would Mr. Cruz or Mr. Rubio suffer because of their inexperience in a nation still smarting from promoting a first-term senator to the White House in 2008? What would a female, Hispanic governor on the Republican ticket, such as New Mexico’s Susana Martinez, mean to the race?

These are questions for the future, but we know the answer to what everyone’s asking now: Yes, Hillary Clinton is running for president.