Advice on where to start

If you have internet, you have a great asset. Google HIIT, lots of videos out there. Also, body weight exercises are wonderful.

I was in the same boat as you. However, I did it for one week with just walking and the pounds began to fall off. I feel great, and its only the beginning. Its so much easier to find motivation once you get started! You just gotta keep with it, and when you feel like you are about to fall off the wagon, find comfort in support from friends. The people I've met on here are amazing!!! Feel free to add me if you'd like!

You can walk or jog, with kids in stroller, push ups, sit ups, leg lifts, squats, jump rope, jumping jacks, dance to music, anything to get you moving. Good luck, feel free to send friend request..

My vote goes to Youtube! There are tons of workouts you can do for free there.

A few to checkout that all offers a variety of great workouts; no equipment necessary.are:
genghisgirl aka Bexlife.
Tiffany Rothe
Sarah Fit
The Sweaty Betties

Good luck

Check out You Are Your Own Gym and nerdfitness.com. YouTube has a ton of stuff. The BeFit Channel has some great programs as well as some Jillian Michaels, Denise Austin, and other trainers, videos. You might like Cassey Ho of blogilates.com. She's a bit perky for me, but she has some decent stuff. A lot of these are 10 minutes or less, so you can squeeze a few in during nap times and such. If your kids are sleeping through the night regularly, I would highly recommend getting up before they do and getting in your workout. Then it's "out of the way", you'll have accomplished something awesome to start the day, and anything else you manage to get in is a bonus.

If you have a double stroller, a walk around the neighborhood is better than nothing and gets you all out of the house. Something that's gone over well at our house (although I've never had two little ones at the same time, we have an 8 year age gap), is using the baby as a "weight". My 4 year old asks to do squats with me, and will climb on my back. She lays on her dad's back while he does push-ups, and she can be used for curls. I also let her lay on my legs while I lie on the ground and do leg lifts and such.

If someone can watch them in the evenings or on weekends, you could squeeze in a walk/run as well.

When they're older, "Dance Party" will be a huge hit, you could try it now. Throw on some music with a good beat and everyone jumps around like idiots. Both of mine (currently 4 & 12) love this.

Check out "you are your own gym." There is a book, and apps for android and apple.

You shouldn't need a gym. think about it like this:

1. Do you have to take the children anywhere? As in use the pushchair to do things like take them shopping? If you do, then brisk (and I mean 3 miles an hour) walking is very good and is one of the many exercises listed in the MFP database. Heck, if the pavement surface is smooth enough, you could even jog with a pushchair (I've done, it so I know you can - you just have to keep your eyes open for faults in the pavement surface).

This is equivalent to the Treadmill at the gym. If you have a smartphone, download the free app called Endomondo and time your walk using that - it will tell you the length of time and the pace, and you can even link it to MFP, so the calories burned are automatically entered into your day.

2. Do you have stairs in your home? Yes? Then run (and I mean RUN) up and down them several times because this will also burn calories.

This is the equivalent of the stepper at the gym.

Alternatively, you can use the bottom step to do stepping, which was a very trendy form of exercise a few years ago and certainly burns the calories. OK, so you won't be able to watch a video whilst you do that but you could listen to something and make up your own routine.

You can't replicate the stationery bike at the gym unless you can beg, borrow or buy one from somewhere - you'd be surprised how many that are sold for very little because the current owner couldn't keep their exercise regime up.

Pilates is also very good for tightening and toning and you can follow videos on YouTube for that. It won't necessarily burn a lot of calories but it is great for getting your posture right and for stabilizing the core muscles at the base of your spine and in your abdomen, all of which will have been stretched because of pregnancy and childbirth.

Another one, as someone else has said, is Bodyweight exercises. If you don't know what they are, here is a link to Wikipedia: http://en.wikipedia.org/wiki/Bodyweight_exercise

There are descriptions of exercises there, so you don't need to buy weights.

If you DO want some weights, what about 2 bags of sugar? Each weighs a kilo (2.25 pounds) and can be held in the hands and hence used for various arm exercises.

Do you possess a longish piece of rope? You do? Great! You have a skipping rope and that is also good exercise. Just about every boxer you have ever seen does skipping to help with the fitness regime.

Will those suggestions do to be going on with?

I can't help overly much with the motivation, other than to say it is YOUR body and if you want it to look good, you have to work for it. I just wish I could do more but arthritis stops me, so I'm telling you what has helped me in the past.

If you don't have a double stroller, can you wear/carry the baby & push your toddler so that you can get in at least a few uninterrupted minutes at a decent pace? I was a bit of a nut about babywearing with my second, and I have more than one carrier that I adored.