An emotional Nikki Hamblin said she was in shock after failing to advance to the semifinals of the 1500m at the Rio Olympics.
Hamblin found it hard to control tears after the race, saying she let herself down with a 13th place finish in her heat after being handily placed for most of the race.
"My whole heart was in that race," she told NZ Newswire.
"I feel that performance doesn't come close to showing what I've put in and what other people have put in for me. I'm maybe in a little bit of shock."
Hamblin, 27, won silver over both 800m and 1500m at the Delhi Commonwealth Games in 2010 but has since battled a variety of leg and foot injuries, one of which ruled her out of the London Olympics.
She said injuries weren't the problem this year.
In fact she believes she may have over-trained in recent months because she had been feeling so good.
"There have been so many tears over the past four years," she said.
"I wanted to compete and that just hasn't happened for me. It's a hard one that four years of work comes down to four minutes of a race. I hurt in a way that I haven't hurt in a race before."
Hamblin was tracking well for most of the race but when the hammer went down at the 300m mark she could not respond and drifted towards the rear of the field.
She finished in four minutes 11.88 seconds, well behind Dutch winner Sifan Hassan in 4:06.64 and nowhere near the top six placing she needed to progress automatically.
Hamblin said she had still to decide whether to contest her secondary event, the 5000m. The heats are on Tuesday.