I am blessed to have some amazing friends who are always there for me, but they can fail to see their worth. These people deal with depression, suicidal thoughts, anxiety, OCD, PTSD, misophonia, and other things that affect their mental health. In all honesty, I hate seeing my friends when they're going through something that seems like it's impossible to get over, or when they're doubting that anyone really likes them. When I see them like this, I've learned that the best thing isn't to try and sympathize or threaten to ruin whatever is making them feel this way. What you really need to do is just be there.
Imagine having period cramps and complaining to a guy about how much it hurts and how annoying it is. If this guy comforts you by saying, "Oh yeah! I totally know how that feels. It sucks," chances are, you're going to freak more because, no, guys don't know the monthly struggle. Now, I may be completely wrong in saying this, and it may not apply to you, but it's the best analogy I could think of. My point is, you really won't know exactly what they're going through, and you trying to, or acting like you do, may make them feel worse in the long run. Sometimes not saying words to justify someone's actions and listening to what they're saying can help more than you think.
Part of me thinks God does this. I know that He shows us how our cup if half full rather than half empty, but He's also always there listening. There's a comfort in knowing that you can say anything to God and He'll listen. He won't try to think of ways He relates, He won't slap you and tell you to man up, He will first and foremost listen to you. As a child of God, what you say and what you feel is important to your Father. When you're hurt and need comfort, God will always be there. Hebrews 13:5b says "'I will never leave you, I will never forsake you'".
But God doesn't stop at just being there. He knows exactly what will help you and He will help you find that. No matter what you're going through, there's always something to look forward to in knowing that God will help you. I'm not saying that he'll always say 'yes' you're asking Him to miraculously make you feel better, because a lot of the time he'll say 'not yet'. He can use your hurt sometimes to strengthen you and give you time, and that time can help you grow in Him and learn more, because life isn't all sunshine and rainbows. If it were that way, there would be something wrong because humans go through crap.
Another thing is that when you find someone who is hurting and asking you specifically for help, ask God what to do. I know, just paragraphs ago, I said that you should just listen, but talk to God. Listen to Him and trust that He will give you words to say, or not say, that will help someone. Leaning on God can't entirely be for your own benefit. You can enlist His help to help others, which is one of the many ways we can show God's love. Although things probably won't end up perfectly, trusting that God will be there will make things a million times better.