However, she said it would be a “disservice” to the country if she did not reassess this closer to the time.
Ms Sturgeon made the comments during an on-stage conversation with journalist Graham Spiers at the Edinburgh Fringe on Wednesday.
She recently fuelled speculation about her future after telling a separate Fringe event she would “make a judgment” on whether to lead the SNP into the next Holyrood election nearer to the time.
Ms Sturgeon became Scotland’s longest-serving First Minister in May.
At an event at The Stand's New Town Theatre, Mr Spiers asked the SNP leader if she ever dreams of the day when she does not hold office.
Ms Sturgeon said: “If I was to sit here and say to you ‘Graham, no, I never have those thoughts’, then I wouldn’t be human.
"Of course, everybody thinks about. You know, if I wasn’t doing the job I’m doing just now, what would I be doing?”
She added: “I don't want to be, and I don’t think I will be, the kind of politician that clings to office just because you’re terrified of the life beyond it.
"In many respects, whenever I stop being First Minister, and I don’t plan it to be any time soon, I’m going to be relatively young.
"So, of course, I look forward to doing other things in the future. It doesn’t phase me – in fact, in some ways, it’s a good thing.
"It’s quite healthy, particularly if you’re a politician, not to find yourself so desperate to cling on to office because you can’t think of any alternative that you end up staying longer than you should.”
Earlier, Ms Sturgeon was asked if there was a danger the public will get “fed up” of her.
She said that is a danger for all politicians.
However, the First Minister said any comments she makes about the future are scrutinised for “hidden” meanings.
She said: “The job I’m doing right now, I am very focused on doing.
"It’s only a year, or just more than a year, since I got re-elected to do this job, and there's big, big challenges, so I’m completely focused on it, completely, 100 per cent committed to it.
"It’s a tough job, but I am privileged to do it, so I’m not thinking about life after that.”
Ms Sturgeon said her “assumption” is that she will stand again at the next Holyrood election, but argued it would be a “disservice to the country” if she did not think about it.
She added: “I think the country would deserve me, at every opportunity where I put myself forward for election, to assess again, am I still the best person for this? Do I think I’ve got the energy and the appetite to do this?”
Elsewhere, Ms Sturgeon spoke out about abuse in politics. She said there was “a nasty, unpleasant fringe” on both sides of the constitutional divide.