Metal rusts faster sitting still than being used. So do skills.

Disuse is not preservation. Something kept carefully in a drawer degrades, and the thing in daily circulation stays serviceable, because use keeps the surfaces clean and reveals problems while they are small. Abilities work the same way. The language you never speak, the instrument in the case, the maths you were once quick at.

Rather than trying to restore everything, pick one skill you miss and give it a small regular slot. Twenty minutes, twice a week, badly at first. You are not aiming to return to your best. You are getting it back into circulation.