Look at the scripture again. I'll give you a second... (1Tim 4:12) Did you read it? What did it say? The big word is "BUT". "But set an example"... See this scripture has less to do with us getting respect for being young and more about us setting an mature, Jesus-filled example of what it means to follow Christ.
The big picture of this scripture is for us to set and example in our lives that blows older (could mean either physically or spiritually) people away! I mean live a life that honors God boldly!
Here's 5 things you can check yourself with. Trust me I will be doing this with you!
1. Speech-- are we honoring God and others with the things we say. (Matthew 15:18)
2. Life-- are we living each moment in accordance to what God would have us live? (1 Peter 1:13-16)
3. Love-- is your heart broken and burdened for your neighbor? Do you deal with people fairly and with honor and respect? (1 Corinthians 13:4-7)
4. Faith-- Do I trust God with what He is doing in my life? Do I forgo my own will and lean on His word and His calling in my life? What in my life shows a life of faith? (James 2:14)
5. Purity-- What do my heart and eyes long for? Do I wish to fill them with selfish temporal pleasures? Or do I walk a life of mental/physical purity? (1 Corinthians 6:18-20)
Lets set an example, then it really won't matter if people look down at us because we are young.