Training v. working out

Okay, so I’ve always enjoyed being in the gym, sweating a bunch and staying in shape. I’ve accomplished my racing goals by being disciplined. Staying committed over months allowed me to successfully complete a variety of endurance races, my proudest being a marathon in 2004 and half ironman triathlon in 2006. That was then, this is now…
Perhaps it is my advanced age, perhaps the increased professional responsibilities, or maybe it is the beautiful little 17 month old I now have, but I have a hard time “working out” anymore. For more than a year, I’ve tried (and failed) to stay in shape by working out consistently. The problem is if I don’t have a race on the horizon and a training program in front of me, I can’t get it done. My workout regimen is feast or famine.
So I appeal to anyone who can help…what’s the secret to moderation in working out? How can I work out consistently and stay in shape without a 12 week training plan? Of note, I am working out feverishly and consistently right now because I have two half marathons scheduled, the Indy Mini in Indianapolis on May 8th and the Dam to Dam in Des Moines on June 5th.