Quick reply, as I'm going to bed lol. To me it doesn't look gloomy, just neutral , or colorless. You have used very desaturated colors, some grey's and reached this scheme that looks almost like overexposed gold or faded photo. It looks good because it is cohesive. Now if this is a problem to you, you could use overall more brighter saturated colors or just saturate some colors more, for example the red of flower or the yellows. When trying this, you can use very small steps to reach your vision. I don't know what medium this is, so this could be your natural way of using colors, technical issue with color mixing or you are afraid of making too garish, candy like paintings. I think you have great control of the overall colors in this piece, so maybe try more unsaturated colors, mixed with grays or not, purposefully.

Yes, if it was me I'd would add just a sliver of saturation (e.g, yellow or violet); you will see that things immediately pop. You might also check out this proko video, "How to Make Colors Vibrate😯" https://www.youtube.com/watch?v=FtQA9_vtREU

Paul, I agree with Rebecca, there are many types of contrast important to the look of your overall piece (as she mentioned like color temperature). So for example you may want to put cool colors next to warm ones to make them pop. From what I am seeing you are using mainly warm grays throughout the image- and using gray is fine however, transitioning from using a warm grey to a cooler one would help create contrast. So for example where you have the dark blackish brown color on the jacket, you may want to pick a blueish black there for more contrast. You also can consider the colors themselves on the color wheel - if you are using blues, opposite that is orange so again, using these together will create contrast. I would recommend checking out James Gurney's book Color and Light for learning about color theory, he is the master at color. Also, trying a few things while working to check your contrast, First, you can turn your image to greyscale - you may see that you have values ranging from 5-9 on the scale but nothing in the 1-3 area (check out the pic I uploaded for reference).Having that range will make your image pop! So maybe you need a few areas of that lighter value. Working with the scale next to your work is helpful practice sometimes. Next, if you are working digital as it appears from your picture, use your color picker/eye dropper to select different areas - is it all showing you picked different variations of a red or orange, but no blues? Then you are using different tones of the same colors and not varying much color. Last, are you working in CMYK or RGB? I ask this because CMYK is less vivid working in digital (I have attached some photos of this as well) so you may also feel there is a vibrance missing just from this color setting. I hope this helps, and I really enjoy your art!

Hey Paul, To be honest with you, I think grey colors are beautiful. Some of my favorite paintings are mostly grey and subdued. Having said that, I agree with @Rebecca Shay, that a pop of more saturated color in the right spot can give the painting life. I am including a painting that I think does this really well. Look how grey and muted the colors are, and then look at that pop of green! Look where it is too, right next to the main focus of the painting, The woman's face. Try this in your own work and see if it helps :)

Muddy colors are usually because there's not enough contrast. You have enough value contrast, so it's a matter of saturation or color temperature contrast. I think little pop of saturation might help. It's a lovely image though!