Volunteering enables you to do other things

Exodus 5:1 And afterward Moses and Aaron went in, and told Pharaoh, Thus saith the LORD God of Israel, Let my people go, that they may hold a feast unto me in the wilderness.

There's a myth that goes around that church planters, evangelists, or anyone to serve in ministry in power cannot do it while employed full-time somewhere else. It's the same logic given to students at whatever level they may be. The devil and even the world have sold them a lie that they should first finish school and then be involved in the ministry. So they wait, and when they get employed, they still wait until retirement, when they get married, they further wait until forever for their marriage to stabilise, then they get children and the wait continues until the children first grow and leave the house. So when will they really serve God? They won't if they don't change their mindset. 

Am forever thankful for my mentors who helped me realise that I can do all these things while planting churches, soul winning, preaching, teaching, and healing. And I did not start today. It started the day I got saved. I have come to conclude that as you grow in stature, grow in Godly service too. You should grow as your ministration grows. I have seen 3 and 4 year old singing and preaching for the Lord on YouTube. I have also seen a similar age singing for the devil. The devil catches them early. We need to catch them early, too, and they should grow along with the ministry.

First, settle it in your mind deeply that you can have your contribution in the ministry even when someone needs you in their workplace the whole day. Otherwise, shunning opportunities given to you to contribute to the ministry means you will never get them in the future. I have come to realise that our current situations are temporal. You are going from glory to glory every year. So don't despair. If you are tied up today, you won't be tied up forever. Tomorrow, you will be self-employed and have enough time to do the ministry without restraint. But I have seen self-employed people rigid with their time because its also a myth that you will have the freedom to do all you want when you are self-employed. 

The Israelites were kept in bondage for years, and Pharoah was not willing to release them to go and worship their God. Pharoah represents the world system. It will never allow you freedom to serve God. You have to escape from it or serve in the midst of it.

Do not allow yourself to live a lie that you will have more freedom in the future, and therefore, you turn down opportunities to serve God today. You can do it part-time. You can volunteer in any capacity as well as you do many other things on the side.

Further scriptures 

Luke 2:52 And Jesus increased in wisdom and stature, and in favour with God and man.

Luke 2:46 And it came to pass, that after three days they found him in the temple, sitting in the midst of the doctors, both hearing them, and asking them questions.