1.翻译：拥有了你在生活/一生中（可以）拥有的（所有）良机,这一定是很有趣的（事情）.
2.该句是一个感叹句.
1）主语：it是形式主语,而后面的不定式短语to have had the opportunities you have had in life是句子的真正主语.
其中you have had in life是不定式中宾语the opportunities的定语从句.
关系代词代替先行词the opportunities,在定语从句中充当had的宾语,所以该关系代词被省略.
2）该句的谓语由“情态动词must + 动词原形be”构成.
3）(how) fun是该句的表语,此时的fun = funny,多用于口语中.