Stack Accomplishments
You need to pile up more accomplishments in your life. It is the simplest shortcut to feeling worthy. People who frequently feel worthless are often those who are not stacking accomplishments in their lives. This does not mean they have never achieved anything. But you must understand that you cannot live indefinitely on past laurels.
Accomplishment is a signal that you are overcoming challenges. It tells you that you are evolving, that you are pushing into new territory. This could be finishing a classic book, learning to code, cooking a complex dish, or simply picking up a new hobby. The antidote to feeling low is to do something that lifts your spirits. And nothing does that better than overcoming a challenge.
The feeling of accomplishment exists because you crossed a barrier. You completed something you once believed was not possible. That is why going to the gym on a day you do not feel like it feels better than going on a day you are excited about it. On the former day, you know you defeated a mental resistance. Identify ways through which you can repeatedly overcome these mental barriers.
The magnitude of an accomplishment does not need to be large. It only needs to be something you were not doing before and finally managed to do. For a non-reader, reading thirty pages a day for a week can feel like a major win. Start a new activity and commit to it for thirty days. Make it engaging by setting milestones along the way. Reward yourself at each milestone. The nature of the accomplishment is irrelevant. What matters is that you overcame a mental block.
Pick a task you find daunting. Break it into a thirty-day plan. Expose yourself to it daily for thirty days. It is fine if you do not master it within that time. The goal is consistent exposure, not perfection. Show up every day without fail. Reward yourself at the end. Get addicted to the feeling of accomplishment. Over time, you will notice it spilling into other areas of your life. The feeling of accomplishment is addictive.