From the perspective of Chinese medicine, physical weakness and feeling tired frequently may be caused by spleen qi deficiency, and the treatment is based on benefiting qi and strengthening the spleen (regulating the qi of the spleen and stomach), which is often treated with Sijunzi Tang and tonifying the middle and benefiting qi Tang. Spleen qi deficiency may be caused by diet, overwork and overthinking. Because of Spleen-Qi deficiency, one cannot transport water and grains for diet resulting in loss of nourishment for the limbs, so one feels weak, mentally unwell and often feels tired. Spleen qi deficiency is treated by benefiting qi and strengthening the spleen, and is often treated with Si Jun Zi Tang and tonifying the middle and benefiting the spleen. Si Jun Zi Tang consists of ginseng, atractylodes, poria, and licorice, and has the effect of benefiting qi and strengthening the spleen. Composed of Astragalus, Rhizoma Atractylodis Macrocephalae, Atractylodes Macrocephalae, Pericarpium Citri Reticulatae and Fructus Aspergillus, this formula is effective in tonifying the middle of the body (treating deficiency of qi by replenishing the spleen), and elevating the yang to lift up the sunken organs. Note that this type of formula should not be taken by patients with excessive heat and evil in the body. If you always feel weak and tired, you should seek medical advice from the hospital and do not take any medication on your own to avoid any adverse reactions.