A day of sun and disappointment

Today started out with my son being as defiant as he possibly could and nothing was going right. So I couldn't think of anything better to do than to go to the gym.
Yes, I said it, I have heard that exercise can lift your mood when you feel down and reduce stress, and guess what, it does, sort of.
I got there and started on the treadmill did ten minutes of intervals getting up to 3.5mph twice and stayed there for a minute, any faster and I would be jogging. I was pretty proud of myself, got off and started on the circuit and added 2 reps to each set at each machine. I am really cooking now. I have never gone this hard before without my trainer. I am going to tackle the elliptical, dun dun dun, this machine is my nemisis. I have never gone more than 5 min on that thing by myself, I was on fire today I'm going for it, even though this machine rattles my confidence, causes my muscles to burn and gets me completely winded. I get up I start and do to min rather slow, speed up to moderate with intent to go for 3 min then one minute hard, come back down to moderate for two and up again finally cooling down to finish ten min. I can do this, I just did it yesterday. I get to the moderate speed the first time and I am going I made it two min and I was feeling the burn, and I just quit, I gave up. I wasn't overly tired, I just felt like I couldn't go on. I said ok, I will finish this cardio interval on the treadmill, then... After two min I quit. What is wrong with me? I started my second set on the circuit machines, and finished that. Then my final cardio I hopped on the treadmill, two min passed and, I quit. By this time I was sweaty and felt exhausted, so I wasn't really upset I did in fact get a decent workout in. By the time I got home I was disappointed in myself, I can do it when Michelle is there, she doesn't get all screamy in my face, quit the opposite actually she is very encouraging and supportive, but why is it that I can do it for her and not me. I mean seriously, I pay her, and not saying she doesn't care on her own, but I pay her to, and I can't do it for myself.
This scares me because my 5 weeks is coming to an end and I am not sure if I can afford to do another session right away. I can do a membership but this was a test of how I would do on my own and I failed. I do want this, I want to be healthy I want to loose the weight. I want to have a baby, healthy pregnancy and delivery and especially healthy baby. This all relies on what I do now.
On the up side, it was a gorgeous day, after dinner my husband drove the kids to the park. It is only a block away but he wanted to make sure both kids got there and back safely. I decided to walk down and join them, afterwards I walked back home. In the past this walk back killed me, not because of the distance but there is a rather steep hill to climb going towards my house. I usually get horrible pain in my legs and knees and struggle to breath, but not today; it took me a literal min and a half to walk that block including waiting on cars so I could cross. I love that I can see those differences.