Now Is The Time

I live in a very rural area. There are a lot of rice fields within a five minute walk from my place. I like taking a walk around here. It is nice to feel the fresh air and see the greenery. I tend to stay home when I have no plans. I definitely have a sedentary lifestyle. As I get older, it's easier to gain weight than before. Now is the best time to start exercising since the weather is getting better.

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1) "a five minute walk"

This sounds more natural than "five minutes' walk".

2) "...feel the fresh air and see the greenery."

You're sentence is not wrong, but it sounds a little more natural with the articles (冠詞) in this case.

You're English is very good!