Tri Tri Again? Or, Y'know, Ever?

Once in a while I'll read something, hear about something, or even do something, and then get a crazy idea.  Once, during a Bikram yoga class, I thought "I should do the 30-day challenge!"  Basically, doing Bikram yoga for 30 days straight.  (There are also 60 and 90-day challenges.)  Now, physically, I think I would've been able to do it.  But then there were things like, oh, work, my family, and the fact that my work consists of teaching fitness classes, and doing 90 minutes of hot yoga PLUS teaching 3 hours of Pilates MIGHT be a bit much.

4 years ago I read about all these running clubs geared toward women, which accepted all levels of runners.  So I started running, thinking I could join a club, get in shape, and make friends.  Except I forgot that I HATE running!  I'm one of those people who counts every second, checking my watch over and over and over, willing time to go by faster so I can just STOP RUNNING!!!! Now, put me on a bike, I'll go all day (as long as I have my padded liners on).  I'll walk for miles.  Spend days in the pool.  But run?  BLECH!!!!
So WHY am I thinking about a triathlon?!?!?!
Blame Rocco DiSpirito.
I just bought his new book, "Now Eat This" (and, no, I'm not getting paid, I have no connection whatsoever to him, except for seeing him on TV), which is full of comfort food recipes, made over to be healthier and 350 calories or less. In the prologue, he writes about gaining 30 pounds (just like me!) and having back pain.  He volunteered to do a triathlon for charity, and has since done many more, losing the weight and then some.  He also appears on "The Biggest Loser," showing contestants how to prepare good, healthy food, which, he says, was a real learning experience for him.
He also mentions that his first tri was a 1-mile swim, 15-mile bike ride, and 3 mile run.  And I thought to myself, "Hey, that sounds doable!"
I also blame Title Nine Sports.  Not the movement, the store. Fitness wear for women.  I drool over their catalogues and sometimes visit the store in Palo Alto.  I've never bought anything, but I want to look like their models, who are "real" women who happen to be incredibly fit and active.  Plus, the clothes are REALLY cute, and very functional. (A reversible bathing suit!  How cool is that! And it doesn't fall apart if you actually go IN the water!)
I also blame my friend Melody, and no, I haven't changed her name to protect her, 'cause she's guilty.  Guilty of completing at least one tri, being incredibly talented, funny, as well as gorgeous, sweet, kind, and having the singing voice of an angel.
If she weren't so awesome, I'd probably hate her.
Oh no I wouldn't!  You CAN'T hate her!!!! She's too awesome!
Anyway, yeah, about 5 years ago she started training for a tri, and completed it.  She emailed us the pictures.  I looked at them, lamenting the fact that I still hadn't lost the baby weight from my second child, who was, at that point, almost 18 months old. 
I was jealous.  I wanted to do something physically excruciating!  Then I remembered, Oh yeah, I'd recently been through childbirth a second time.  And staying awake WAS excruciating!  Plus, I worked out every morning, ran errands with baby girl in tow (have you ever tried getting a car seat in and out of a 2-door car multiple times a day?) then pushed 2 kids in a stroller all over creation every afternoon, AND giving baths every night.  I was doing the Mommy Tri!

But now the kids are older.  They walk on their own, and their pretty good at staying with us and not running away.  We can take them to the playground and actually sit down once in a while. Basically, I can't use them as my workout regimen anymore.
And I'm getting older.  I'm post-40 now, and while, mentally, 40 is the new 12, physically that just isn't the case.
And the fact is, I DO want to challenge myself!  A tri isn't just demanding physically, it is mentally. as well. So, I need some opinions up in here:  anyone do a tri? Want to do one? Training to do one? Am I crazy?  Should I stick with walking? Is whining and kvetching considered part of the training regimen?
Any advice would be greatly appreciated.