Looking for McGyver (cross post)
No, really.... I have a pressing personal problem for which there might or might not be a viable solution. Since I'm only 5' tall, my bike's wheels are 24" - otherwise I can't touch the ground with my feet on both sides at once. You don't want to know how many times I wrecked a 26" bike. Well, if you do want to know, I'm not telling. Can't count that high. And I don't trust cable brakes so mine are coaster.
Also with the passage of time, I'm less able to deal with the hills around here, I need some kind of AFFORDABLE pedal assist. I've spent hours hunting a suitable rig online and have finally decided to admit defeat.
So any bike enthusiasts and/or engineer types out there who can help me solve this, I'd appreciate the help.
= new reply since forum marked as read
but it looks like you've got a thread there and some answers.
But also try the Bicycling group here as well. Might get even better answers there, because I don't know enough about either rigging something or messing with a bike to make something you'd need. Good luck wherever you find the help! 
The frame is what is fitted to the person.
You may need to go to a frame size that is correct for your height and torso length.
There's a lot of oversimplification in there, but a competent bike tech should be able to get you fitted correctly.
Unfortunately, there may be a bit of expense involved if you need a new bike.
My wife is quite small (5'1"
and she has what is called a 'mixte' frame; instead of coming straight back to the top of the seat post, the top bar comes down to meet the rear axle housing.
I know this isn't a "You just...." type post, but I hope it can at least provide one point of reference for you, even if it's an outlier.
Best of luck. Bikes are great exercise, and a lot of fun.
I was mixing up my terms in my head. What I was thinking was the actual size of the frame itself; the distance from the center of the crank to the top of the seat post, not the wheel size.
But there may be some hope: The bike you have may be close enough to fitting you if a good tech can adjust the components. You might need a seat post or stem that is capable of letting the seat or handlebars be adjusted to you. Sometimes they can be gotten inexpensively with patience and searching.
I admit that I went to a derraileur bike many decades ago, but being a 'guy', the 'gadget to fiddle with' part was attractive.
Being able to cusomize the gear for the conditions took time to learn, though.
Just as an aside: Have you insured that there isn't anything out of sorts with bike as it is? I had a lot of pedaling resistance from a rental bike on a vacation long ago that had a very rusty chain, for example. Could you simply need to lube the chain, or adjust something?
I truly wish you the best of luck in finding what works for you.