When John Aalberg took part in the 1994 Winter Olympic Game, how old was he?
how old was he refers to age; 1994 Winter refers to games_name = '1994 Winter';
SELECT T2.age FROM games AS T1 INNER JOIN games_competitor AS T2 ON T1.id = T2.games_id INNER JOIN person AS T3 ON T2.person_id = T3.id WHERE T3.full_name = 'John Aalberg' AND T1.games_name = '1994 Winter'