One of the most consistent ways research has demonstrated to increase connectivity in the brain is to learn new physical skills. Controlling the body in space appears to be particularly good at stimulating the growth of new synapses (and possibly new neurons as well, though the research is not conclusive here outside the hippocampus). Yoga is a good start. Modern dance, breakdancing, capoeira and gymnastics are all excellent if you're slightly more athletic.
Beyond that, practicing thinking in different ways really helps your brain develop. One thing that most people neglect is geometric/mechanical intelligence. Get some 3D puzzles, and once you get really good at them, start building simple machines. If you never got good at math, trying to pick up some advanced mathematics can be a good exercise as well.
Beyond that, practicing thinking in different ways really helps your brain develop. One thing that most people neglect is geometric/mechanical intelligence. Get some 3D puzzles, and once you get really good at them, start building simple machines. If you never got good at math, trying to pick up some advanced mathematics can be a good exercise as well.