@Mrs. D. - with you 110%. Our boys are 4.5 and 1 right now and we're in the thick of it too. The brunt of the daily grind has been falling on DH and we had a big talk about it the other night. Basically from sunup to sundown he's constantly in motion doing stuff for one of our kids or us as a family - making the coffee, loading the car, getting one of the kids dressed while I do the other one or nurse the baby, then either doing the daycare/preschool drop offs or heading into his (unsatisfying but flexible) job for the day (while I do dropoffs). Then in the evening, it's contending with our cranky 4yo (his mood really suffers when he's tired/ in the evenings and it's like walking on eggshells to avoid setting him off), getting dinner on the table, coaxing the 4yo to actually eat his dinner, then putting the baby down, then cajoling the 4yo to take a bath (some nights more of a fight than others - and we only do baths every few days), then going through the lengthy bedtime routine for the 4yo which DH handles (snack, stories, lying down next to him for awhile). Once all that's done, it's time to clean up from dinner, pack lunches for everyone for the following day, get daycare food ready, do any needed laundry, etc. Maybe a little time for shows before our bedtime of around midnight. Whew! It's exhausting just typing it all out.
One way we are coping is by loosening our MMM-like ways for the time being. That means:
-not shopping around for the best deal or insisting on getting used stuff always (instead of new via Amazon)
-takeout McDonald's on the way home from daycare pickup once a week
-hiring a housekeeper to come every other week (haven't made this official yet but am planning to start it this month)
-hiring landscaping help for our fairly unruly yard (even though we swore we wouldn't be like all our well-to-do neighbors who have paid landscaping crews every week...oh how the mighty have fallen!)
-not spending a lot of time analyzing our spending and crunching numbers in Excel
-trying to plan more regular 1:1 date nights (we do lots of social things with our friends in groups but are not as good about "dates" - I'm starting to see this as an investment in our marriage, which otherwise has hit some rough patches just juggling all of the above)
So yeah, we feel like MMM failures sometimes but also are keeping our eye on the prize - our own happiness and wellbeing, which for now means throwing some money at the problem even if it delays our FIRE date.
For me, it's been really helpful to incorporate the following:
-bike commuting to work 2-3 days a week (almost 10 miles each way so a great workout, even if it adds some time to the commute; keeps me from having to find other time to workout)
-audiobooks and podcasting (sometimes while bike commuting -- most of my route is on a protected bike trail so it's relatively safe and I leave one ear open)
-reading instead of watching TV or aimlessly surfing social media (feel so much more accomplished when I finish a novel or other book)
I will say I feel like we're turning a corner now that our youngest (and likely last) is over a year old. We can let our 4yo play in our yard by himself (until he insists that we come out and play with him anyway...), he recently got into real (small) legos which keep him occupied for long stretches of time, and the baby is super easy going and happy to explore and easy to entertain (with finger foods or toys for ex.). There's light at the end of the tunnel!