Do you remember a period in your life when you were 'on fire' for the Lord? At that time prayer was easy, penance was easy, giving away hard earned money was easy.
So what happened?
I think it's the same as what happens to a bowl of ice cream or a plate of hot soup - we went back to room temperature.
What's the solution?
Jesus gave it this morning in the Gospel: remain in my love.
And how are we supposed to do that?
Jesus also said: If you keep my commandments you will remain in my love.
On the feast of the Ascension Jesus will say to his disciples: teach them to observe all the commands I gave you. He didn't say: teach them to observe some of the commands I gave you; nor did he say: teach them to observe all the commands that suit them.
Are you keeping all the commandments? If you're not then you're not remaining in his love and sure as melted ice cream is yukky, you'll end up at room temperature sooner or later.