being happy整个可以做sth,it is...这个固定用法并不适用于这个句子,整个句子主语是Learning how to relax yourself 谓语是is,然后to being happy是做宾补,to要作介词用,介词后面动词为ing形式.那在it is essential to do sth里面其实真正的主语是 to do sth，这句话就是 to do sth is essential？
现在的句子 sth is essential to sth ，然后to 是介词，后面加ing？可以这么说。