By Father John Catoir | Catholic News Service

The kingdom of God is within you. We've all heard this truth, but few of us fully understand it or make an effort to put it into practice when we need it. In signing off my letters to friends and others, I often write, "May the Lord be your strength and your joy."

For me, it is a way of reminding people that they can rely on the Holy Spirit to do their heavy lifting. In order to protect yourself from needless worry, you have to know how to enjoy the present moment.

I recall this quote attributed to Thornton Wilder: "My advice to you is this, don't ask why or wither, but just enjoy your ice cream while it's on your plate. That's my philosophy."

And I tend to agree with that sentiment. Yes, God wants us all to carry our cross, but with courage. We need to banish needless worry. A holy person is one who listens to the words of Jesus and strives to obey them.

If you have trouble with this, begin with the simple statement: Yes, Lord, I want to be holy.

Once you say yes to God, your main task is to trust him. Trust is the purest way to show your love. Keep in mind that the enemy of trust is doubt. Doubt can cloud your best intentions and weaken your spirit. It is basically a fear that you may be a fool for believing in the supernatural or in something that can't be explained.

Don't be taken in by those who urge you to doubt everything unless you can prove it scientifically. Remember that as Catholics, we believe in mysteries. And keep in mind that others have never been able to prove scientifically that God does not exist. It's not for you to ask why they pretend to be so sure that there is no God.

What you can and should do is take responsibility for your holiness and happiness. Train your mind to believe and to trust God with your whole heart. Don't live in the mental swamp of doubt and guilt. If you do, I can guarantee you that you're always going to feel miserable and unworthy.

Strive for a clean conscience and be active about your holiness. To do this, renew your good intentions, go to confession. And then begin the process again, even if you stumble a few times.

Never say, "Why do I have to go to Mass?" That's the equivalent of saying, "Why do I have to thank God?"

Remember that God has given you everything: your life and your ability to love and be loved. Attending Mass is the best way to say thank you to God. The Mass is a ritual of thanksgiving, which comes naturally when you let go of worry, when you learn to trust in what the Creator has in store for you.

God wants you to live gladly because of his love. Put on the will to take charge of your thoughts and be more positive, more uplifting, more trusting. I promise, the reward will be great.