However you tends to define gambling, it would be incomplete if stakes, risks and challenging activities (competitions) are not mentioned.
You can defined it your way but my interest is to understand this>>> Are sports games or related competitive activities which stakes are involved between both sides or teams also gambling?
Remember, there would be a winner to be rewarded and a looser to lost the stakes.
Gambling is an activity that involves betting money on something. So if there is no money in it then it is not gambling. Gambling always involves two parties where one wins and the other loses, so there is risk and money in every gambling
If we bet money on a match then it is gambling, but if we are football players and take part in the match then it is not gambling even though when we win the match we will get a prize.