Tai Chi Benefits
General: 
“[Tai Chi] teaches inner strength while toning muscles, increasing flexibility, and boosting immune power. It is also said to reduce stress, store up energy, increase body awareness, and improve balance and coordination.” 
Psychological: 
Relative to baseline levels, [Test Subjects] reported less tension, depression, anger, fatigue, confusion, and state-anxiety; they felt more vigorous, and in general they had less total mood disturbance.
Immune System:
 A study conducted in China indicates that Tai Chi may increase the number of T lymphocytes in the body. Also know as T-Cells, these lymphocytes help the immune system destroy bacteria and possibly even tumor cells.
Balance: 
After adjusting for fall risk factors, Tai Chi was found to reduce the risk of multiple falls by 47.5%. "Many Tai Chi participants provided anecdotal testimony on aborted falls' events, independently reporting awareness of both the environment and appropriate body maneuvers in the presence of unexpected perturbations.
Arthritis: 
No significant exacerbation of joint symptoms using [Tai Chi] was observed. Tai Chi exercises appear to be safe for rheumatoid arthritis patients...weight bearing exercises have the potential advantages of stimulating bone growth and strengthening connective tissue.
Tai Chi can significantly reduce arthritic pain. Tai Chi helps reduce arthritis pain by increasing circulation and stimulating repair of damaged joint surfaces. "In addition, it stabilizes joint structure by strengthening the soft tissue support of the joint… Less pain promotes greater physical function of the affected joint and decreases the adverse mental health affects related to living with arthritic pain.
Cardiorespiratory Function: 
Practicing Tai Chi regularly may delay the decline of cardiorespiratory function in older individuals. In addition, Tai Chi may be prescribed as a suitable aerobics exercise for older adults.
Strength and Flexibility:
“Cardiorespiratory function, strength, flexibility, and percent of body fat were evaluated before and at the end of this study. Cardiorespiratory function, strength, and flexibility improved significantly in the Tai Chi group … our data indicated that Tai Chi training could result in an increase of 15-20% in strength of knee extensor/flexor. Although Tai Chi practice needs no instrument and employs only postural change, it can significantly enhance the strength of lower limbs. 
Blood Pressure: Systolic and diastolic blood pressure decreased over the 12 weeks of Tai Chi practice.12, 13
Bone Density: Tai-Chi as an intervention to increase bone mineral density (BMD) in a healthy female population; Regular Tai-Chi exercise improved total hip BMD.14