After an illness, the body needs strength to recover, which it mainly receives from food. It is good to drink a course of multivitamins (two months). It's summer now, so a great solution would be to nourish your body with fresh berries, fruits, vegetables! Also now there is a large selection of balms and syrups for immunity (with natural compositions), which would also be good to drink in a course!
First of all, you need high motivation. Of the drugs, tinctures of Rhodiola rosea, ginseng, Chinese magnolia vine, Eleutherococcus have proven themselves well. Eleutherococcus can rightfully be called a storehouse of useful substances. In Soviet times, it was used to train cosmonauts, divers and other representatives of extreme professions. This is not surprising, because the strengthening and tonic effect of the plant has been scientifically proven.
Exercise in the fresh air is also useful.