Thank you Larxene so very much(!) for this in depth look at these character elements. Alongside with what Cap added, I found myself very much in what you both said... yet I cannot hide the sadness that it brought me...
Given your Saturnine qualities, that is a natural response. It is okay. Joy and sorrow are part and parcel of life.
What do you think would be a wise approach to the hindering effects of Saturn and all that you've stated? In the end it's a matter of will right?
Practically speaking, I suggest first learning to realise what is important to reflect on, and what is unnecessary or not very useful to ponder about. The idea is to minimise what's called analysis paralysis. There are things that cannot be changed, and there are things where very little can be done by you to change it. The example of the first is the past. Whatever mistakes we did in the past, we cannot change. We can only amend the resulting consequences. In the same way, whatever past misfortunes that we experience cannot be undone. We can only tend to the wounds. Another thing you should avoid doing is thinking about things that you can do little to change. For example, recently I read the news about murders happening near where I live. The more I ponder about it, the more saddened and disgusted I become. But then I realise, there's not much that I personally can do about the murderers or the dead. It is better to use my reflective character to think about something else that is more productive.
This sounds simple, but it is not easy to do. It took me several years to differentiate my thoughts, and learning how to redirect one's thoughts takes practice.
Aside from this, if your slowness is a problem in your career, then you need to gauge how much you can do within a particular period, and to complete tasks according to your limits. Don't try to do too much. You may have a perfectionist tendency. Here again, is where you need differentiate between what needs to be near perfect, what can be good enough, and what is unnecessary to do.
Astrologically, you can do what Christopher Warnock calls "planetary charity". This is a ritualistic process of giving alms to someone that is associated with the planet you want to appease. This is based on the Hermetic worldview though, and you may not hold that kind of worldview. Here, your problems are Saturnine, so you would give alms to a Saturn-like person, thing or organisation, in order to lessen the effects. For more information, click the link I provided above.
If you ask me, no, it is not a matter of will. Rather, it is about understanding the kind of person that you truly are. Then, it is a process of trying to live according to who you are, and avoiding the temptation to try to be what you are not.