You are at a fork in the road.
One side leads to success. The other side leads to murdering your joy, your dreams, your aspirations, your goals by pretending that you are not who and what you are. You can put your energy on one or two places:
1) trying to find WHY you have doubts that cripple you or
2) gather up all that is inside of you and force yourself to do the work but do not make it bigger than what it is. That only will lead to being overwhelmed and that leads to murdering the artist in yourself. It IS life or death but you will make the decision to live or die as an artist and following that path. You will have to make choices and decisions every day and perhaps every hour but it is as simple as a thought in the direction of your destiny.
As you progress toward your life as an artist, you will gain confidence and strength. Evaluate your assets and also your deficits. In reality, negative people or negative thoughts or criticism are enemies to your goals. You don't need to attack them but you do need to not let them affect you any more than single a drop of rain would. It is insignificant. Small changes, building over time, lead to the fulfillment of your goals. This is just how it works. It has been said that patience is the cure for frustration. Part of knowing the rules of the game is knowing that playing within them works. Violating them leads to frustration, losing time, and pain.
You may have made the tasks appear larger than what they are and have caused yourself overwhelm or you may have thought of a longer runway than what it actually is and have overestimated time. It takes less time and effort than what it feels like and you could only know that had you already achieved your goals. So, you must have some faith and belief of the possibility of this being true.
We are not born walking but we do walk. You can only build on success but it is incremental, never instantaneous. You are today, where you are on a path to success. For some reason the plan or the map has not been clear. Let me know if you need help with that and we can implement a myriad of sequential steps, done within a time frame.
The first step is to make a decision. That sounds simple, in and of itself. It is. However, the word decision, can be made to mean that you cut off all possibilities of NOT doing what needs to be done. When you "don't feel like doing it" or do not do it, you are going the wrong way and are literally creating unhappiness and possible failure. The thing to do is to act. Action is much more powerful than thought in the achievement of goals. Don't get this wrong, though. Thought is very very powerful and is capable of either starting or stopping your progress. The best thing is that thought can also help you change direction and to keep you moving in a straight line to a goal, instead of being distracted from it.
You need a rigid and unchangeable policy in place to handle any pattern which is stopping you or slowing you down which can include both thought and action or the lack thereof. Without a policy of how you operate as an artist, you will be subject to every little whim of yourself and others and may wake up one day, still lying to yourself that you are too old and that it is too late. Now is the time, your time. It is the only equal asset that the living have. Use it and prosper or waste it and suffer the consequences.
Write down your policy for yourself and let me know what it is.