I finally have a little bit of spare time now, andso I have checked part ofsome recent messages.

After reading Memory's messages, I've been worrying about her so much.

It's more natural to use "have been worrying" here.

Health is everything and no, because a healthy body means a health noy life, so. This is the reason that what Memory should do right now is (to) have a good rest; be away from your phone and computer.

In the meantime, please do exercise as much as you can, and set it as a regular routinedo it regularly.

We usually say, 'make it part of your daily routine'.

I hope you get well soon, and be healthy for your entire timecontinue to always stay healthy.

This sounds a bit more natural👍

Since I finally have a little bit of spare time now, and I have checked part ofsome of most recent messages I've received.

"Part" would mean that you read only some of a message (like 30-40% of it at most) instead of reading all of it.

After reading Memory's messages, I've started to worry about her so much.

I chose "I've started to" because it seems that Memory's messages are the reason you're worrying about her.

Health is everything and no health no life, so, so what Memory should do right now is to have a good rest;sleep well and be away from youher phone and computer.

I was debating on how to fix this sentence, so I'm curious to see others' takes on it.

In the meantime, please do exercise as much as you can, and set it as a regularmake it part of your daily routine.

I hope you get well soon and bestay healthy for your entire time.

I finally have a little bit of spare time now, and I have checked part ofsome of my recent messages.

After reading Memory's messages, I am so worryied about her so much.

To worry about smth focuses on the action; to be worried about smth focuses on the feeling/emotion.

Health is everything and no health means no life, so what Memory should do right now is to have a good rest; be—stay away from youtheir phone and computer.

Semicolons are used to separate things that could be sentences on their own. Here, since you're trying to rephrase/elaborate on "have a good rest," the correct punctuation to use is an em dash.

In the meantime, please do exercise as much as you can, and set it asmake it a regular routine.

Why are we suddenly switching to you from her? Were the first two sentences just the introduction?

I hope you get well soon and be healthy for your entire timestay in good health.