I don't have kids, so I can't advise on the post-pregnancy component, but BOY can I help out with the "running-enjoyment-impaired" part of your post. I've always had a hard time with the running component of tri-training. I VERY rarely have that great running workout where I'm actually glad to be out there the whole time, but at least when I first started there was that "I can't believe I ran a whole mile without stopping" series of small goals to keep me motivated. Just before we moved (2 years ago) I had a stress fracture halt what was the best running season I'd ever had. The combination of the move and the recovery process totally derailed me, without my training partners, coach and running routes I just stopped running and basically took a year off. This last fall, I started picking up the pieces and trying to rebuild that base and it has been so much harder than it was the first time around. It is so hard to be happy with getting out there and doing it when it's slower/harder, etc.
So here are some of the things that have worked for me:
1.) FORGET that you ever ran before, just don't think about it. Force yourself to focus on the fact that you are doing it now and find SOMETHING to be proud of, even if it's "I got off of the couch." (That little phrase really helped me out this winter... )
2.) I have the "ten-minute" rule - (Now it's expanded to the 20-30 minute rule if there's a longer workout on the plan) The basic principle is that if I'm having a crappy run, I only have to keep running for ten minutes and then I'll re-evaluate. After ten minutes, I can take a walk break or whatever will help. Very rarely have I ever quit the workout ten minutes in, but I have made it a walk/run workout, if that will make it better.
3.) Find someplace special to run, there's an amazing park that's not at all conveniently located to my house that I initially would drive to so that I could run someplace really gorgeous. It definitely helped motivate me to have something new to look at, and be on a route that I didn't know how far I had yet to go.
4.) On the same theme, I would make special playlists on my i-pod that I only got to listen to when I ran. If you can find something that you only get to do on a run, even if it's peace and quiet, emphasize that. Anything to make it more special/fun/motivating.
5.) Let yourself do run/walk workouts. You just had a baby, you are a freakin' rockstar, so if you're struggling with a run workout, modify it. There's no shame in it, especially if you plan it from the get-go.
Consistency is my biggest struggle as well, so I really feel your pain. I have the same issue where I'll be really good for a while and then get totally derailed, so the above tips have helped me dust myself off and get back out there. Ultimately, that's really what it's all about - getting out there and having a good time.
The beatings will continue until morale improves