I was operated 3weeks ago(microdiscectomy),when can i start doing some exercises and what do you recomend to start with?

Check with your MD: However, most basic exercise can start under the guidance of a physical therapist which should be prescribed by your MD since you would like to be more active. In the interim, walking, ellipticals, bicycling and swimming are safe non impact exercises to start with. PT would focus on core strengthening and could slowly evolve into a Pilates based regimen.

Exercise s/p back su: ~3 weeks is a time frame for incision healing- there still are lifting restrictions and muscle strength limitations ( no more than 5 lbs) for several more weeks. See enclosed guide https://www.hopkinsmedicine.org/orthopaedic-surgery/_documents/patient-information/patient-forms-guides/JHULumbSpineSurgeryGuide.pdf Discuss w/ your MD