I can't speak for anyone else, but here's how *I* maintain a healthy lifestyle, that includes sometimes doing things when I'm tired or unmotivated. In fact I was thinking about this today, as I was reading a post from someone who said "I don't like to cook and won't do it."
Here's my philsophy:
If you had a friend who chronically lost jobs because he just didn't "feel like" going to work, who was always struggling with money because he couldn't hold down a job, and who was always talking about how he just didn't like to work ... wouldn't you say to him: Dude - suck it up. Pull your heat out of your butt and realize that no one gets handed a living on a stick. Go get a frickin' job and be responsible like the rest of us.
If you had a friend who said they hated balancing their checkbook and living on a budget and just never did it - waiting until they ran out of money, but was always complaining because they were hit with overdraft fees and never had the money to do the things they wanted to ... wouldn't you say to that friend: Look, I get that you don't like balancing your check book, but quit bitching to me about not having any money if you're not going to take responsibility for yourself.
But for some reason, when exercise and diet are concerned, we're not allowed to have the same - pull your sh*t together reaction . For some reason it's supposed to be ok for people to abdicate responsibility when it comes to weight and health. And I don't get that.
We all do a lot of things we don't like to do because that's what you HAVE to do to live your life as a responsible adult. We all do some form of work to earn money - even on the mornings that we don't want to climb out of bed and go, we do it anyway because it's the responsible adult thing to do. We all pay our taxes because we don't want to wind up going to jail for tax evasion, even though paying taxes sucks. We all pay our mortgages and rents and electric bills and gas bills and so forth because we don't want to be living in a cardboard box under a bridge - even though we'd rather use that money for something else. If you have kids, you don't decide that you're just going to ignore them one night because you don't feel like dealing with them - you act like a responsible parent.
To me that's what being healthy is. Sometimes I really enjoy exercising. Sometimes I really enjoy cooking meals and experiments. But sometimes I drag myself home from a really crappy day at work and I don't want to go to the gym and I don't want to cook. I just want to order a pizza and wallow in self pity. But I don't ... just like I didn't skip work that morning just because I felt like crap or didn't pay my phone bill because I'd much rather buy a pair of new shoes.
Doing the right thing ... the thing that's best for you ... is not always fun. Hopefully you can find ways to enjoy it most of the time; most people don't loathe their work all the time, and we appreciate being able to pay the mortgage because it's a roof over our heads. But on those days when it seems like an unbearable weight, you just do it anyway, because it's the mature, responsible thing to do.
I dunno. Maybe that doesn't work for a lot of people, but it works for me. I don't have to LIKE going to the gym every single day I go - but I go anyway. I don't have to LIKE cooking, I just have to do it and fuel my body. So on those days I may eat a scrambled egg rather than fix gourmet baked chicken, but there you go ... it's just what we do.