What a great command -- go encourage someone. There must be someone in your life who need encouraging. If you can't see anyone ask God to open your eyes. And then if there is still no one, then ask God to bring someone to you you can encourage.
I looked up feeble in Hebrew. It doesn't really mean physically. It means someone who is weak emotionally or spiritually, someone who has failed; someone who is stumbling in their life; someone who is despairing, someone who has lost hope; even someone trapped in sin.
What would life be like if everyone on this planet lived like this? What if everyone chose to live outward rather than inward, living in hope rather than greed?
How do you encourage? Come alongside someone. Listen. Then pray for them. And if they are open to listening to you ask them how God has worked in the past, how God has provided for them in the past. Help them remember the goodness of their lives. Then, tell them the promises of God. Help them believe.
If we did nothing else in our lives but this, we could say at the end of our lives, we lived very good lives.