For those who are not sure how to unlock this achievement, all you have to do is level your Sim up to a level 3 Athletic skill, and then use the “Good Pacing” interaction when exercising (Running, Jogging, Tredmill etc). Good pacing does the trick. Good luck!
Achievement: Spring Training
Description: Is your Sim fit enough to run a marathon? Your muscles may be saying no, but your willpower says YES. Remember to hydrate and stretch!
Expires: August 12th