Did Act 1 and Act 3 Side bosses for Spirit but i still only have 30.

I noticed I still only have 30 spirit even though i am in act 4. I did both of the bosses to get the initial 60 and even when back and re did them to make sure i got he item to gain the spirit. I still only have 30 spirit and don't know how to get back the 30 im missing.

Which class do you play?
Look also in Character's spirit halved or Missing Spirit.