Recently, I’ve been busy with my daily life.

It’s only painful to continue endlessly suffering.

I wish I could take all of the pain away from them.

I’ll say, that it’s a miracle for you to live every day.

Also it’s happy for youIt's joyful to live with a smile on your face.

Living a Life

I’ve been thinking that to live is sometimesit is sometimes difficult to live.¶
OR¶
I've been thinking about how difficult it sometimes is to keep living.¶
OR¶
Sometimes I find it difficult to live.

Yours is grammatically correct, but it flows better to have 'to live' at the end of the sentence. 'to live' sounds very formal when it is used in the beginning or middle of a sentence.

'I've been thinking that..' means you held an opinion for a while and then that opinion just recently changed. "I've been thinking that those plants were flowers, but I just learned they're really bad weeds!"

'I've been thinking about...' means something has been in your thoughts a lot or that you have been pondering a topic. "I've been thinking about you!" or "I've been thinking about how we are going to solve this problem".

'I find it' is what google translate says your Japanese meant. This is more personal that the others. This is a more formal way to say 'I think that it is difficult FOR ME to do something'. It limits your opinion to your own abilities. For example, "I find it difficult to speak Japanese" means that you struggle to speak Japanese, but not that you think Japanese is difficult for everyone.

It’s only painful to continue the endless suffering.¶
OR¶
It's only painful to continue suffering endlessly.¶
OR¶
There is only pain in continuing to suffer endlessly.

I know how they feel.

'I know how they feel' means you have personal experience with the same feelings they are experiencing. If you don't have that experience but are still aware of and sympathetic to their feelings, it's more natural to say 'I understand how they feel'.

I don’t know what to say to them, but I just want to listen and to be with them.

You don't need the second 'to' because it was already said in the first phrase with 'to listen'. When listing phrases, anything shared between all the phrases only needs to be said once. In the examples below, I put the words they share in parentheses. Notice how in the combined sentence, those shared words only appear once.

(I want to) listen
(I want to) be with them
I want to listen and be with them.

(I want to) listen to (them)
(I want to) be with (them)
I want to listen to and be with them.
'I want to listen to them and be with them' is also okay

I wish I could take all of the pain away from them.¶
OR¶
I wish I could take all of their pain away.

#1 is grammatically correct but wordy
#2 is a more concise way to say the same thing

I’ll say think that it’s a miracle for you to live every day.

You could also use 'I believe' or 'I consider it to be a miracle for you to live every day.'

I’ve been thinking that ito live is sometimes difficult to live.

Some people are struggling withe to livinge their lives.

It’s only painful to continue endless suffering.

You could combine these two sentences to read better:
"They sometimes want to give up on living, because it is only painful to continue the endless suffering."

I don’t know what to say to them, but I just want to listen and to be with them.

I wish I could take all of the pain away from them.

I’ll say think that it’s's a miracle for you to live every day.

Alsond it’s happy for youwonderful when you are able to live with a smile on your face.

"It's happy for you" does not really make sense. Some things you could say:
"It's fantastic when..."
"It's amazing when..."
"I am grateful when..."