The best way I can describe it is that despite your best intentions, interests, and drive, you have a unnatural deficiency of positivity and optimism when processing things. You rarely give yourself the benefit of the doubt when approaching things in life. Whether this is day to day activities and decisions or long term life goals. You will then take these feelings as weakness and begin to judge yourself immensely whenever things don't go exactly the way you want them to.
The proximity in which you feel like this directly represents the severity of the depression you have. Not everyone is the same but most would have near daily occurrences of the above aforementioned.
Another aspect of depression which may not be true for all but was true for me, is that while perhaps not right away, you will eventually feel solace in your depressive episodes. It oddly feels good to feel bad, but perhaps good isn't the right word. Comfort fits better. Difficult to explain why, really.
To overcome you must first admit that you are not okay with feeling the way that you do and you would like to get better. The biggest hurdle is to cast aside the self-judgement. This is no easy feat but it is certainly the most important thing you can do towards getting better. Stop judging yourself as best as you can. Learn to forgive yourself. Reinforce that you deserve to be happy. Work on processing thoughts slowly and as thoroughly as you can but remember to give yourself time and to forgive your shortcomings. Not at all easy but a necessity when it comes to overcoming depression.
Find a physical activity, any activity that can get you moving. MAKE THE TIME FOR IT. Ping pong, biking, frisbee, walking, dancing, depending on your comfort with social situations - a team sport like soccer, basketball, or volleyball can be a huge help. Start by doing this physical activity ONCE each week for 30 minutes. Slowly increase as time goes on. I've dealt with depression during most of my adult life and each time I allow myself to workout I feel better.
Admit your feelings and allow them to come naturally. It can be very easy to overthink things and be indecisive. Do your best to make stern decisions on the best information you have at the time, and stick with them. This will instill confidence in who you are. This will not be perfect and you will make mistakes. The most important takeaway is not to be overly judgmental/hard on yourself when you fail and to learn as much as you can from the experience.
Love yourself. Take pride in your accomplishments, no matter their size. Enjoy life as best you can and strive to be happy.