Martin Lloyd Jones on the terrible error of making your feelings central

Avoid the mistake of concentrating overmuch on your feelings. Above all, avoid the terrible error of making them central. Now I am never tired of repeating this because I find so frequently that this is a cause of stumbling. Feelings are never meant to take the first place, they are never meant to be central. If you put them there you are of necessity doomed to be unhappy, because you are not following the order that God himself has ordained. Feelings are always the result of something else, and how anyone who has ever read the Bible can fall into that particular error passes my comprehension. The Psalmist put it in the 34th Psalm. He says, ‘Taste and see that the Lord is good.’ You will never see until you have tasted; you will not know it, you will not feel it until you have tried it. ‘Taste and see’, it follows as the night the day. Seeing before tasting is impossible. That is something that is constantly emphasized everywhere in the Scriptures. After all, what we have in the Bible is Truth; it is not emotional stimulus, it is not something primarily concerned to give us a joyful experience. It is primarily Truth, and Truth is addressed to the mind, God’s supreme gift to man; and it is as we apprehend and submit ourselves to the truth that the feelings follow. I must never ask myself in the first instance: What do I feel about this? The first question is, Do I believe it? Do I accept it, has it gripped me? Very well, that is what I regard as perhaps the most important rule of all, that we must not concentrate overmuch upon our feelings. Do not spend too much time feeling your own pulse taking your own spiritual temperature, do not spend too much time analyzing your feelings. This is the high road to morbidity.
— Martin Lloyd Jones, Spiritual Depression: Its Causes and Cure