1Co 2:4 And my speech and my preaching was not with enticing words of man's wisdom, but in demonstration of the Spirit and of power:
1Jn 1:3 That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ.
From these two verses it can be seen that evangelism involves:
Telling people what Jesus did and taught
Demonstrating it: healing. casting out demons0 and through t his show The Kingdom of God has come
Doing it so that people can enjoy the same relationship with God that you have
Telling people what Jesus has done in your life and can do for you,
Any other reason is not a valid one as it will not be based on God's quality of Love for t hem.
If you love others in the way God loves them you will do all you can t o save them from going to hell and your objectives in life will be based on helping others to avoid hell and deal with the problems Satan gives to them. God promises to provide all your needs if you wholeheartedly/do this.
The fact you cannot carry these objectives out at the time is not important. The important thing is to do them when God gives you opportunity to carry them out.
So Jesus asks:
Are you doing these things when you can?
What are your purposes in life?
Do you demonstrate The Kingdom in your life
Do you tell others about me and what I have done when th e opportunity arives?
Are your objectives my objectives for you?
For you sake I hope they are