How to say "it's a function of ..." in Chinese?

The algebra analogy "it's a function of X" seems commonly used in daily conversations in English but it's rare to say "X是Y的函数" in non-mathematics context in Chinese. What would be an idiomatic translation?

For example, how would you translate this sentence said by the former Bulls coach Phil Jackson, in respond to the question what made him more nervous, as a coach or as a player:

"Definitely as a coach. ... your energy is a function of what you are doing. As a coach, you are just participating through your mind."

Instead of X是Y的函数/X是Y1,Y2,Y3的函数, would it be a good option to say Y决定了X/Y1,Y2,Y3共同决定了X?

Full context:

Jackson was asked what made him more nervous, his first Finals as a player or as a coach?

“Definitely as a coach,” he said. “I was much more nervous as a coach. When you play, your body is involved. You’re running. You’re energized. You’re playing the game. You may lose focus or track on the floor, but your energy is a function of what you are doing. As a coach, you are just participating through your mind.”

In daily conversations, we do not use "甲是乙的函数", instead, we do use "甲取決於乙" for something that we think is crucial.

Translation of the sentence said by the former Bulls coach Phil Jackson:

• @droooze As a answer to the question what made him more nervous, as a coach or as a player, we can omit "作為(as)" in the response in Chinese. And where is the "definitely" in "作爲教練" as a translation? Commented Jan 6, 2019 at 2:22
• Nevermind, I didn't see the whole context and read the meaning wrong. Commented Jan 6, 2019 at 2:58

Short answer: don't say 'is a function of' in Chinese. 'depends on' springs immediately to mind, 'is related to', 'comes from'. All that adrenaline coursing through your arteries!

Jackson was asked what made him more nervous, his first Finals as a player or as a coach?

Definitely as a coach,” he said. 绝对是作为教练的时候，他答道

“I was much more nervous as a coach. 我当教练的时候紧张得不行

When you play, your body is involved. 当你打比赛的时候，你全身心地投入。

You’re running. 你得跑。

You’re energized. 你充满能量。

You’re playing the game. 你在打比赛。

You may lose focus or track on the floor, but your energy is a function of what you are doing.

As a coach, you are just participating through your mind.” 但是作为教练，你只是在你的脑海中演示比赛。