Doing LOOP in Stored Procedure

Code

DECLARE v_start int default 0;--Start month
DECLARE v_end int default 12;--End month

set v_start = 3;
set v_start = 6;
--[BEGIN] LOOP
L1: loop

if (v_start > v_end  ) then leave L1;
end if;
set v_start = v_start+1; 
--DO SOMETHING 
END FOR;
--[END] LOOP