楽しんでいるなと思います（なの意味）

Question

これは私の個人的な印象ですが、みんな本当に生活を楽しんでいるなと思います。

I was wondering what that な is standing for.

Answer 1

In meaning,

これは私{わたし}の個人的{こじんてき}な印象{いんしょう}ですが、みんな本当{ほんとう}に生活{せいかつ}を楽{たの}しんでいるなと思{おも}います。

＝

これは私の個人的な印象ですが、「みんな本当に生活を楽しんでいるな。」と思います。

This 「な」 is a common sentence-ending particle used to casually conclude an impression/opinion.

"This is just my personal impression, but I think everyone is really enjoying his life."

Like many other sentence-enders, 「な」 all by itself could not be translated easily. You would only need to know it is used for a casual kind of conclusion.

Answer 2

An extension to the "casually concluding" な explained by @l'électeur

Short answer

な adds the nuance/emotional quality of "I wonder" to the sentence, be it positive, neutral, or negative. Granted, the way the "wonderment" is added is not a hard and fast rule, and varies by context. Note that in the English versions below, the "wonder" may seem contrived, but it's only to illustrate the point.

Negative connotation examples

For negative expressions, the "I wonder" can be a "sarcastic softener", as can be the case in English:

• うるさいな～

It's really noisy (and I wonder if you can turn down the noise for me, thanks).

• うるさいな～ v2

I wonder if you can stop talking, thanks.

Positive/neutral connotation examples

• いいな~

That's great! (I wonder if one day I might be able to have that too!)

• やってもらえるかな

(I wonder) if you can do that for me.

• みんな楽しんでいるなと思います

I was wondering to myself, "It looks like everyone's having a good time"

• わるいな

Thank you, (but with the following packed into it: "Sorry for making you go through all the trouble of doing me that favor. I wonder if (hope that) you won't hold it against me.")

• すごいな

Wow, that was cooooool. (I wonder how he/she did that?)

Answer 3

We might be able to understand it by comparing the one with it with the one without.

• 生活を楽しんでいると思う: I think they enjoy their lives
• 生活を楽しんでいるなと思う: I find theym enjoying their lives

The latter implies that you have such impression by observing how actually they do something, while the former doesn't necessarily so. So, you can conclude that な stands for an impression formed through observation.