First, adjust your diet structure, mainly to increase the intake of fat (meat, milk, eggs, seafood) and sugar (biscuits, rice, steamed bread and other staple foods) in protein;

Second: improve the body fat rate, knowing that being too thin is also an unhealthy performance;

Third: aerobic activities should be carried out at intervals (running, skipping, swimming and aerobic are strongly recommended), and attention should be paid to step by step;

Fourth: gradually start the resistance movement, that is, lift the iron (this can be put aside for the time being)

To make a reasonable plan, you should know your general situation, height and weight, and the overall physical quality level.

That's all. If you need guidance, you can write privately.