Don't live in the past (or the future)!
Do not say, "Why were the old days better than these?" For it is not wise to ask such questions. Ecclesiastes 7.10
I once heard a 10 year-old say to a friend: "When I was young the summers were so much better..." It goes to show that nostalgia - or the tendency to see the past through rose-tinted spectacles - is not necessarily an affliction of age! But it is debilitating nonetheless, if it distracts us from making the most of today.
The truth about Christian living is that the best is always yet to come. Here again we must be careful not to run towards the opposite extreme to nostalgia, which is obsession with the future. Paul got it right when he explained to the church at Philippi: "I am torn between the two: I desire to depart and be with Christ, which is better by far; but it is more necessary for you that I remain in the body." (Philippians 1. 23-4) In other words, despite our cherished memories and our hopes for tomorrow, God calls us to focus on today and living faithfully and compassionately among those he has called us to serve now.
You might wish you were somewhere else, back in a simpler more innocent age, or in heaven where there will be no more suffering or crying or pain. But if your calling is to inhabit this moment, this place, this family, this workspace, pray instead for courage, patience, grace and vision to enable you to do what you, like Paul, know is "more necessary" for the moment. Jesus himself urged us not to worry about tomorrow (or yesterday) but to keep our focus on the dawning of God's Kingdom today!