Truthful talk here. I’m the opposite of the super motivated exercisers even though I do some form of workout 6 days a week. Can’t truly say there is ever a time I’m raring to go and can’t wait. Instead, I tend to come up with excuse after excuse after excuse about why I shouldn’t workout today. Some favorites: it looks like it might rain, I’m feeling a little off, it would be so much fun to do _____ (anything!) instead, my asthma is worse, I do not want to get sweaty, and on and on. If tomorrow researchers discovered a pill that kept us all physically and functionally fit without having to get off our couch I would consider selling my grandmother for access to that pill.
But… there is no magic pill and I know how much better I feel when I actually make myself exercise. Both immediately after and just in general throughout the day afterwards. I like being able to do activities with my kids and random adventures. And I’m hoping to avoid some of the health issues that run in my family.
So about 90% of the time I lie to myself. Flat out lie. “Just go and do 10 minutes. After that, you can stop if it’s raining/you don’t feel well/whatever.” The interesting thing is that once I’ve made myself start there has never been a time when I’ve actually quit after the promised 10 minutes. There are (rare) days when I actually don’t feel well after the 10 minutes and do a slower or easier workout, but I’ve never felt awful enough to quit once I started moving. And most of the time after the 10 minutes the workout actually feels pretty good, better than expected. But that’s not surprising given I always expect to die during the workout; low expectations are easy to exceed.
And here’s the real kicker - I’ve never once felt worse after a workout. If I can make myself move and do something (even if it’s slower or easier than planned) then 100% of the time I feel better physically when I’m done. So that reinforcement helps.
If you’re just starting out, you’re going to feel awkward. Things are going to hurt. You will have more excuses not to than learned reinforcement. So for the first few months you have to use whatever tools work for you to keep you going through the bad first few months. Tell your friends so they’ll keep you accountable, get a buddy, pay for a trainer (if that’s in your budget), make a literal appointment on your calendar and lay out your clothes the night before. Whatever gets you going for the first few months. After those first few months hopefully you’ve developed a habit or at least experienced some of those moments where you feel better to give you the reinforcement to go on.
Just start. And don’t stop. Simple, but not easy. 
Oh, and for me - variety helps. If I had to do the same workouts for the rest of my life, there’s no way I’d survive. I mix in all sorts of things. For a while, I’ll run more often and maybe even increase distance for a “race”, for a while I’ll focus on stairs seeing how many I can do in a session, for a while maybe I’ll take up paddleboarding, for a while I’ll get a block of some sort of class I’ve never done before. I’ll take my kids for a walk and we’ll climb on things we find. Whatever, just mix it up.
