Do people 'see you and rejoice?'
Because of the topic we're studying, I frequently remind the women in my Bible study of Jesus' summary of 'the most important commandment' in the Bible: "Love God with your whole self AND love your neighbor as much as yourself" (Matthew 22:37-38 creative license taken). Jesus went on to say in verse 40 that, in fact, all of the other laws can be and are fulfilled if you simply obey this one. So, when Psalm 119:74a says [People] who fear God shall see you and rejoice, it means that people will rejoice because they've seen you Love God with your whole self in some particular circumstance. It means that they'll rejoice once they've seen you love your neighbor as much as you love yourself.
What's key to learn here is that simply running out and doing some act of goodness does not fulfill this commandment (and will not make you right with God). It's when God's love for you SO fills you that you can't help but love your neighbor as much as yourself. It's then that people will see you and truly rejoice because they've seen that your act of goodness is out of pure love for what's been done for you.