How do I start exercising?

Walking where and as you can is a good start.

If walking outdoors is out, start with standing and moving through your house or apartment.

If balance is a problem, start there. On YouTube, there are physical therapists (real ones) named Bob & Brad. They have videos (and printouts on their web site) of balance exercises (among lots of other physical therapy things you may find helpful). In the spoiler below, I'll put a couple of their balance videos. (Putting them there just so they don't take up a big screen space in this post.)

They have others, and so do organizations like AARP or Silver Sneakers.

On YouTube, you can also find videos of chair exercises of various types, or exercises for seniors. I'm not saying you're a senior because you're 58. (I'm a decade older than that myself). I'm suggesting those exercises because they're oriented to the situation you describe, having mobility and balance limitations. You can use them to improve, and as you do, you'll be able to take on more challenging things.

I think I can somewhat understand how you're feeling. I started exercising regularly myself quite late (late 40s) after a sedentary adult life then full-bore cancer treatment that had left me very, very physically depleted. The thing is, I don't think motivation is what's called for here. It's the commitment, discipline and consistency to work at it.

You start with whatever is manageable, just a slight challenge. Maybe that's only a few minutes every other day. That's fine. One of the hard parts (for me, anyway, and maybe others) is swallowing one's pride and admitting what the current state is, and not feeling bad about what we can do out of thinking it's not good enough. Thinking it's not good enough leads nowhere (at least nowhere good).

If it's a slight challenge, it's plenty good enough. Do that, and you'll make progress. It may be slow at first, but it'll happen. As what you're doing gets easier, add a little something to make it still a challenge, but manageable. (I'm talking about going a little longer time, going further, doing a different exercise that's a little harder, doing something more frequently - whatever. Not all of those at once, but that kind of thing.)

Another option, if it's affordable to you, would be to find a trainer who is experienced in rehab, and hire them to work with you. That may sound scary, but it can be very effective.

Just chipping away gradually, you will amaze yourself at where you'll be in 3 months, let alone a year and more. It's worth the effort: Freeing. Independence-enabling. Great stuff.

There have been other people your age here who started with big challenges, and achieved more than they ever dreamed possible at the start. (I'd actually say that happened for me, too: 45 year old me would be gobsmacked to see what I'm able to do at 68, what my active life is like.)

You can do this. It will pay off. Start now. Keep it up.

I'm cheering for you to succeed!

I started at 56, obese, sedentary and with illness-related joint issues. . I was already doing daily stretching and basic yoga a couple times a week.l, but simply getting out of bed was painful and awkward.

Luckily, we had an old fashioned “rice” bed. If I hadn’t been able to hand-over-hand those giant four posters, I’d never have made it out of bed and to the bathroom in the morning. And I can’t tell you how many times I slid down the stairs on my butt because I couldn’t make them standing.

I started just walking. A little here, some more the next day or week, until I found myself walking about fifteen miles a day during pandemic. I’ve cut back the walking as I’ve increased other workouts and movement.

See, that’s the thing with movement and exercise.

If you’re not moving, it becomes harder and harder - and less appealing - to do it.

Witness my mom. Atrophy started with her legs and feet from lack of movement, worked its way up to hands and arms, and I don’t mean to scare you (actually I’d really like to scare the world into listening) but it moved up her body til she could no longer swallow and passed away.

OTOH, once you start moving, you begin to crave movement. It doesn’t take much.

There’s a lovely post here by an older woman who started by vowing to walk to her mailbox, then added a fence post, a street light, the neighbors mailbox, until, to her shock and delight, she reported she was walking a couple of miles a day.

My husband was obese and sedentary, too, until his late 60’s. For some reason he tried Tai Chi and LOVES it. He liked moving so much he started doing the aquafit classes at our gym. He enjoys it so much. He’s like a little kid in the water. Total personality change from sober thoughtful adult man to splashy, playful, jokey kid. And the lucky (I mean, hardworking) man is developing killer thighs from these two activities and his walking.

If he misses a class, he is frantic to find another because he has to move now. Me, too.

I am so grateful for these massive changes in our quality of life and health, and sincerely hope you find your way to them, too.

TL:DR you can continue being sedentary and obese, and piss and moan about it while maintaining the status quo, or get off your bottom and change your future. Does an illness control you, or do you control you?