I've been meditating ever since I became a buddhist, so that would be about 12 years.
There are 2 forms of meditation, samatha and vipassana. Samatha is meant to calm the mind down and stop irrelevant thought, vipassana is meant to give you insight, to see things without prejudice. To reach vipassana, you must first practice samatha. The mind needs to be still before you can start thinking again. The Jangama dhyana is a samatha, but it's quite difficult since the area between your eyebrows is quite small and not particularly sensitive. It would be a better idea to start with Anapanasati (mindfulness of breathing). Being aware of your breathing is a lot easier and less frustrating to start with. This does not mean it's less good. I as a reasonably advanced meditator still use it at least once a week.
This site contains very good information regarding Anapanasati and various other types of meditation:
https://www.wildmind.org/mindfulnessIt will guide you from the beginning stages to the more advanced stages (stage 0 to stage 4). To start off you should meditate about 5-10 minutes in the morning and 5-10 in the evening, but this is also described on the website.
There is a lot more interesting information on the website, and I would recommend you to look at the information about meditation posture before you start. Posture is very important in meditation:
https://www.wildmind.org/postureThe benefits can be achieved after just a few weeks. The longer you meditate, the more skilled you will get. Meditation is like an endurance sport for the mind, with regular practice your mind will be in better shape. It may take effort in the beginning, but stick to it. It'll really improve every aspect of your life.
I'd prefer this to Tai chi, chi kung etc which seem like a lot of effort for something you could do better with explosive exercise like weights and presumably hard martial arts.
Tai chi is focused on the mental aspect, not the physical aspect of sports. So you could never do the same thing with weights. Furthermore, Tai chi can contain lots of explosive movement, it's just that the solo form which contains primarily slow movement is the most well-known.
P/R
Meditation is originally a religious practice.