OP, have you tried a little challenge, like the 30 Day Shred or something similar? Something that's a good workout and will show results relatively quickly?
Slightly off topic... I just want to take a moment to point out the first rule of 5Ks for new runners: Never, ever
, pick out a person at the beginning of the race and think "well, at least I can beat them!" Particularly if that person is overweight, north of 70 years old, barefoot (!), or pushing a stroller containing triplets.
Stroller lady has passed me in two different races and I've been trounced by more retirees than I care to think about!