I had the same hesitation for a long time, so I get it! But bottom line for me, having it on the calendar and having to GO somewhere to do it keeps me accountable. AND I'm paying for it, so if I haven't canceled or rescheduled within 12 hours out, I'm paying for it either way and may as well go.
Club Pilates is where I go. They do a free intro class for newbies weekly, and it took me a good three months to finally make myself go. I signed up on the spot for a four-class monthly pass. Scheduling is all on the app, and even if it looks full when my monthly passes hit, I have never had a waitlist not come through.
As for benefits, it's actually fun! It's a combination of fairly light strength work (springs, light hand weights, ball, body weight) and flexibility/balance work. The latter has really helped my running. The work on the reformer with the straps really helps you hone in to which side of your body is weaker. It forces you to find a balance and do the work evenly. And there's quite a bit of mat work with some classes/instructors with heel raises and other balance exercises that is super complimentary to running. There's always a lot of good stretching in between movements, too. I've found the instructors and classes that are challenging enough, so if the intro feels a little easy, know that you may need to ask other members or try a few classes to find your right fit(s). They also have class levels (1, 1.5, 2), and after four months I'm feeling confident enough to sign up for a few 1.5 level classes. If you get REALLY into it, there are one-on-one classes too. My studio doesn't do a hard sell, but ymmv.
If you think you want to try it, I have a referral code. I'm not sure what it gets us, but can't hurt:
https://members.clubpilates.com/auth/register?referral_code=cp-cwsse