If I stop doing what is mentioned above - eat well, sleep well and exercise - I too get stuck in a rut instantly. It also helps to have clearly written down what result you are after on Audiojungle (and in life too), for example decide on how big income and how big portfolio you are going to have. Then write down the purpose, or WHY you must have this; maybe you want to become financially independent, by doing what you love the most? Maybe you want to live in Thailand, and open up a studio? This will become your fuel to push through any rut.
Another thing that really helps is the mindset of always “producing for the trash bin”. What I mean is, do not expect to make each track better than everything you have made before. You are just producing for the love of producing, and trust that over time your quality will steadily go up as you gain experience.