There are a lot of Christians in the universal church who think they have nothing to offer. Part of it is that we've made too much of ministries that are public. We listen to someone teach, and we think, "I could never do anything like that." We think, "I could never disciple somebody; I'm too immature." As a result, a lot of Christians don't do anything at all.
The problem with that is that God has given a purpose for every single Christian in His church. And if one person is not doing what he/she is supposed to be doing, the whole body suffers. Every Christian is indispensable.
Consider what Paul writes,
...the parts of the body that seem weaker are indispensable. (1 Corinthians 12:22)
What Paul is getting at in this illustration is that those ministries that aren't so public are often looked down upon. But just like body parts that aren't so prominent are still indispensable, so gifts that aren't so prominent are indispensable. The church needs everybody. Giving someone a meal is not useless. Keeping things organized is not useless. Making upbuilding conversation with someone is not useless. Everything you do for the cause of Christ (provided it's not contrary to Scripture) is beneficial. And you must use your gifts, otherwise the church body will suffer for it.
Praise God that He has made every Christian indispensable, according to His purposes, to the praise of His glorious grace!