There’s no such thing as ‘be in the moment’ or ‘live in the moment’ because you are inevitably living in the present — every moment of your life — whether you dwell too much in the past or future.
When you state ‘live or be in the moment’, you are indirectly suggesting that we live in the past or future and that we need to put ourselves in the present moment to live it—every time.
Such philosophies have been misleading people for too long. What you are actually trying to inquire is ‘how to be alive every moment’. If that’s your concern, all you need do is to —
“Realize deeply that the present moment is all you have.” by @eckharttolle
No matter what you do in your life, you can only do in the present. Past and future are only in your memory and imagination respectively. The past is long gone and the future hasn’t come yet.
What you are left with is the present, which is made out of moments. So, all you have to decide now is ‘how alive you want to be every moment’.
That’s all there is!!