Every day I'm more and more disappointed in myself for not living up to my potential

I think very few of us ever live up to our full potential.
What any human is capable of is pretty awesome, but it takes a hell of a lot of effort to get there, and there are always obstacles and challenges along the way.

The only place we can start from is right here and now,
with whatever resources we have in this moment.
As an ancient Chinese saying goes, the journey of a thousand miles starts with a single step.

I think of many achievements as like shelling baby peas; it takes many tiny actions to fill a bowl,
but the result is yummy.

Work out what takes priority, set yourself that goal and work on it gently, day by day. If you have a setback, be gentle and forgiving of yourself and just start again from a place that feels easy.
If you choose exercise, within about three to six weeks you will start to feel a bit more energy and bounce.
Use that to add in one new project; something fun and enjoyable.
Maybe give yourself rewards like a walk in an especially beautiful place, a visit to the zoo
or anything that peaks your interest.

It's easy to get into a rut, I do it all the time.
Try to write down what you want to achieve, break it down into small steps and work through them one at a time, you can quickly get into habit of completing the things you want to do

Take a look at how miserable and even laughable people who exceed their natural potential are.