Meet yourself where you are at.
Seems pretty obvious right? But so often we expect ourselves to be at the goal before we've even started. We hold ourselves to actually impossible standards in doing that. The only place to begin, is exactly where you are right now.
Forming new habits involves rewiring your brain. It is like forging a new path in the woods. Imagine the trail that has been well worn, it's quite an easy way through. Now imagine the wilderness where no trail has been worn. Forging a new path through that is a real struggle. It's really hard at first because of the uneven surface, fallen branches, rocks, shrubs, little critters and bugs, probably some spider webs, tall grasses, guaranteeing you to get pretty scraped up and maybe take a few tumbles.
But eventually, after a long while of diligently following the same route through this untouched territory, a path is formed. Each time you take this path, it becomes easier and easier to continue on it. And eventually, it's the only way you choose to go. This is the same way new habits are formed. It's the way our brains form new thought processes and structure any neuropathway. When a neuropathway is repeatedly used, it becomes more automatic.
Once a habit has been formed, it takes a lot of effort to diverge from it and form a new one. The old path is still there, and it's definitely easier in many ways to continue taking it. But it is not easier emotionally when you desperately want to form a new path, a new habit. If you keep forcing the new route, the trail will eventually form and be as engrained as the original. Abandoning the old path is the way to allow it to overgrow, become the wilderness again. Doing this will make it even easier to use the new path. Your brain wants to take the quickest route to solve a problem, and if you've trained your brain to take the path you want it to by repeated action, over time it overgrows the old trail and allows the newly formed trail to be the choice one.
This does not happen overnight. It requires much patience and persistence. Dedication and diligence. Actually getting up when your alarm goes off to get in those early morning miles. Giving yourself enough time to do your strength and mobility exercises. Eating the nutritious post run meal instead of the kind of gross but also delicious egg McMuffin from Mickey D's.
The bottom line is that you can make a decision to do right by yourself. And in order to actually follow through with that decision instead of forgoing it and ending up with a feeling of self-loathing and disappointment, you must form these new habits. Repeated action through patience and persistence will allow you to make the decisions on the daily that you feel satisfied with. It all starts where you are at now.