Hello
What do you exactly mean when you say Weakness...
Is there any stress?
Are you taking enough sleep/ rest?
Have you done any blood tests recently?
My suggestion is that you should meet Some Good Physician nearby, who will examine you and take a proper history and advise certain investigations accordingly like
Thyroid,
Vitamin D n
B12, Blood
Sugar, etc.
Health Tips
Take lots of fruits, sprouts in your diet.
Also Dry Fruits like Almonds, Dates, Figs will help you improve your stamina.
Do regular Pranayam and Meditation which will also help you feel better.