Stress
Don't worry, this job is only stressful on days ending in "y." Your routine will consist of twelve to fourteen hour workdays and lots of takeout. Everything is building up to the big day, and if your candidate loses, you'll be out of work.
Understandably, you'll probably encounter a colorful variety of panic attacks, meltdowns, and crying jags (some of them yours), so it helps to keep a level head and take care of your health. All the travel and late nights can take their toll on relationships with loved ones and possibly on your job, if campaigning isn't your primary career.
Your judgment may be questioned by campaign staff, political supporters, and the candidate—or even Mr. or Mrs. Candidate—and if anything goes wrong, all fingers will be pointed at you. But for those who love it, election planning is an exhilarating, high octane profession. When everybody celebrates the new guy or gal in office, you'll be smugly aware that this day would never have arrived without your awesomeness.
And hey, if you come in second, you can always try again in the next two to four years.