Why Does This Feeling Stay With Us?

SubhanAllah, for as long as I can remember, I've had these heavy feelings in my heart-loneliness, sadness, and depression. They come and go, sometimes staying a long while, sometimes shorter, but they always seem to come back. And I know, alhamdulillah, my life is filled with blessings. Allah (SWT) has given me so much, truly everything. There’s an ayah that keeps coming to mind: 'And He gave you from all you asked of Him. And if you should count the favours of Allah, you could not enumerate them. Indeed, mankind is [generally] most unjust and ungrateful.' (14:34) So why? Why do I feel this chronic sadness, this weight on my chest that makes everything feel so heavy and paralysing, even when I try my best? I try to pray my salah, to be a good Muslim, to read Quran, even to pray Tahajjud sometimes. I try to have sabr and be grateful. But the feeling remains. I know, and I ask Allah for protection, that ending one's own life is haram and is not the path. That’s not what I mean. Maybe what I’m realizing is that so many of us are struggling in our own ways-with our iman, with our mental and emotional state, with our spiritual connection. And yet, by Allah's grace, many of us have a roof, food, safety. We're not in a war zone. So what is it that leaves our hearts feeling so restless and unsatisfied? Where does this deep lack of contentment come from?