Tingling in the hands it is a really annoying symptom that can happen all the times, frequently or from time to time. For example if you lean with all your body weight on your left arm eventually you will start feeling tingling or that feeling that my arm fell asleep why? It is because pressure on the nerves. Sometimes when we sustain a repetitive movement that can cause some tingling especially in the feet. However I want to bring you into attention that sometimes tingling can be caused by pressure on some other part of the body. For example if you have sciatica or a pinched nerve pain you may experience tingling down the feet.
My recommendation is daily movement. When you move you are taking pressure off the nerves and increase blood circulation leading to a better functioning. Stretch daily especially lower body muscles such as calves, quads or hamstrings. In addition you can step on a tennis ball and alleviate soft tissue pressure if you feel the tingling you need to stop.
Sometimes tingling is caused by low blood pressure or low levels of calcium.
Your second question how to make a body fit? Easy: stretch daily, move daily and add some fitness movements to increase better functioning of the neuromuscular system
I hope this answer has helped you and hopefully the tingling stops when you start stretching and moving