Four years ago, the Scot was left out of the Great Britain Olympic team for Beijing in spite of posting the qualifying standard, and on Saturday in Rome, the 26-year-old knew she had to medal at the Modern Pentathlon World Championships to get the qualifying mark for London 2012.
Not only did she do so, but she struck gold, the first British woman to win the individual title since Steph Cook in 2001.
Spence was joined on the podium by English team-mate Samantha Murray, who won bronze, and three British girls have now achieved the Olympic qualifying standard, Inverurie's Freyja Prentice having managed it at last year's European Championships. Prentice finished 16th in Rome, but now finds herself down the pecking order with only two places available in the London team.
Spence admits she hit a low after missing out on Beijing and had to work her way through it using the sports psychologist at the GB base at Bath University.
"It was a really tough time for me," she said. "I really did question what I was doing and if 2012 was really an option for me.
"I questioned my ability as an athlete and it did take quite a while for me to fight back and that's when I started working harder with the sports psychologist to find myself and figure out what I was wanting to do.
"I'm really glad I found my way through that situation and I know I've put a lot more into the last two or three years."
Spence went into Saturday's final as the top British qualifier but had to prove herself all over again.
She was in third place going into the final event, the combined run-shoot and produced a tremendous display to overtake France's triple world champion, Amilie Caze, in the final kilometre of the race.
Spence was 37 seconds behind before the event and left the shooting range the final time just two seconds behind the Frenchwoman.
She took her on early in the final 1km run and then went away from her towards the end.
"People were cheering me on coming down the home straight at the end and I found some extra energy somewhere," said the Scot. "I just kept fighting and fighting all the way."