I thought about making gigantic round space station that would spin when it moves that could form an artificial low level gravity. Steroids combined with mandatory weight training from young age could solve the problem of weak muscles in a low gravity environment. I'm not sure what to do about weak bones in a little gravity environment. I'm also not sure about what would power the stations. I was thinking solar on nuclear energy but I'm open to ideas. And then there would be the problem with food. I'm not sure how a low gravity environment would affect plant life. It's possible that earth plants will not survive in that type of environment. I'm not sure what other source of food you could use to sustain human life in outer space. Any ideas?
There are only two technical preconditions to allow humans to live in space: Low cost structures, and closed life support systems.
Low cost structures mean that there will actually be a place to live. If buildings and space stations are built to current aerospace standards and launched into orbit using current technology, then (according to Rocketpunk Manifesto) the average cost of space hardware will be about $1,000,000/ton. This makes even a tiny, one bedroom apartment pretty unaffordable to the average space blue collar worker.
Work arounds include balloon structures like the Bigalow aerospace habs, or perhaps better still, water filled balloons which use water as both the thermal moderator (heat circulates throughout the water and keeps the interior at a steady temperature) and as radiation shielding (about 5m of water is needed according to "The Millennial Project: Colonizing the Galaxy in Eight Easy Steps by Marshall T. Savage"). The Neofuel site suggests making the balloon in the shape of a bagel and letting the water freeze for structural integrity (http://neofuel.com/ICESHIPS/index.html). In most cases, using local materials (from the Moon, and later on asteroids and comets) will reduce the costs considerably, especially since far less energy is needed to move bulk supplies in free space compared to lifting it from Earth's gravity well.
Closed Life Support Systems (CLSS) is the second technology needed, since having cheap living space is meaningless if you have to spend all your resources importing consumables to live. Consider the ISS needs regular supply runs from Russia or the United States to keep the astronauts aboard supplied with food, water, clothing, fresh oxygen and water, recycling canisters for the air system and so on, as well as to haul away the garbage. While you and I can go down the street to various stores (which are at the ends of gigantic supply chains themselves), people in space are much more limited.
Being able to recycle a large fraction of your waste products and get food, water and oxygen in return will reduce the need to import consumables considerably. Even a CLSS which is only 80% efficient (which is probably the best we could do with current state of the art) would massively reduce the need to import food, water and oxygen. Stuff like clothing, computer hardware and high tech equipment will probably be imported for decades to come, but in terms of shipping space and bulk will be a small fraction of the resources needed for life support.
Once we are at that level (and assuming there is a feasible reason for being there in the first place), then the main technology needed for long term living in space is low cost space flight, using high ISP engines like ion drive or even momentum exchange systems like Solar Sails to move material to your space habitats. These materials from asteroids, moons etc will provide the raw materials needed to carry out economic activities, to expand and grow and to make up the inevitable losses from CLSS systems (topping you up with fresh water and volatile elements for the system to continue functioning).