As a mom, you have all the motivation you need. You just aren't looking in the right place. Now, hear me out, I'm not attacking you. Heck, I once WAS you. Sometimes, the motivation is right in front of us and we never see it until it is pointed out, sometimes, too late.
August 13, 2012 will forever be in my head. I was 29 and my daughter was 3. I had sent my husband on to work, telling him I would watch our child, despite the fact I wasn't feeling right. He left the house around 4am to go to work and I wend back to bed. Earlier that month, my daughter had come down with strep thoat for the B strand. Shortly afterwards, I had started feeling ill and after several repeat visits to the doctor, was told I was only suffering mild allergies. As a severe asthmatic, I took that at face value. I want to point out, before I go much deeper into my saga, that I wanted to lose weight prior to this date, but lacked the moviation and played the "I've tried everything with no success" card several times already. Anyways, moving on.
I had went back to bed once my husband left the house. I don't know when she got up that morning. I just know that when I woke later that morning, around 8, she had managed to pull my large 293 pound frame off of the bed and nearly to the floor. She was screaming, she was cryng, she was in a lot of distress, apparently, she had been doing this for a while. I was in a fog and had managed to shuffle both of us out to the car. I don't remember the drive. I do however, remember walking into the doctor's office and watching the entire office freak out and 911 be called. I remember hearing "Oxygen is at 42! Get the mask!" and vaguely think that was a low number. I remember being carted off, strapped down in a gurney, while a stranger detained my screaming child who was trying to get to me, knowing I didn't have the strength to even call her name out.
I ended up with streptococcus pneumoniae. My left lung had 90% blockages and my right lung had 75% blockages. I was in ICU and on life support. My O2 saturation level was indeed at 42, a level lower than most corpses entering the local morgue. I developed ARDS, which is short term, but short term is relative, it can take 1-5 years for full recovery with 90% of patients never fully recovering. I fought for my life for 2 weeks before I was released from the hospital. I was then returned home being told by doctors to file disability and that I would forever be on an oxygen tank.
I believed it all. Until the day I finally could see my daughter again. Her tears, her hugs, her love changed it all. I was on an O2 tank until mid to late October. I took baby steps to exercise. And I do mean baby steps. I couldn't walk from my room to the couch with out passing out do to my oxygen dropping. I would increase my walks by 10 seconds at a time. My first true "walk" was 1/8 of a mile that took nearly 30 minutes. I started dieting. I started adding more exercise in. I started doing it all because of my daughter. She almost watched me die. And my asthma was a reason...but I would have never gotten that bad had I weighed less.
Today, I am 70 pounds lighter. I still have to monitor my oxygen. I still have dangerous drops, asthma attacks, and ARDS flare ups, but not as frequently. I don't have any function in my upper left lobe of my lung. But that's okay. I run, have to carefully monitor my heart rate, but I run. I can get between 3-5 miles in 3-4 times a week, and usually between 35-55 minutes. I do modified HIIT (again, have to watch my heart rate) and strength training. I am healthier today than I have ever been in my entire life, despite the fact I nearly lost my life a year ago.
Everything I do, is for my child. It isn't for me. If it was I would have done this a long time ago. My child is my motivation. I don't want her to live my life. I teach her to eat healthy, the importance of exercise (she's my exercise buddy even

), and I make myself tell her what is and isn't "mommy approved diet" foods...and she will correct me every time. So I am accountable to her.
You say you don't have motivation. I say, look down by about two to three feet. The best motivation of your life is right there in front of you.

Been there, done that, understand. I know you can do it. I know, because I did. And I still am.