CHRONIC DEPRESSION AND LOW SELF ESTEEM

DEAR SIR,

I am 18 years old boy. i am suffering from depression, low self esteem,lack of motivation,forgetfulness,social anxiety & nervousness for a long time.
I was very lonely and shy from my childhood and used to communicate with people very hardly, for this reason i used to masturbate frequently.
Now i am doing graduation (B.A 1st year) but my study and concentration are being affected by this mental health issues.
i was not habituated with any healthy physical exercise but now i am going for morning walk for 2 months which is giving me very pleasant feeling.

thank you for listening my problems and i will be very grateful if you can help me with your precious advice...
your faithfully
P.K. DEY