Anxiety from feeling like I'm not achieving enough

I've had anxiety for many years now (I'm 26) but lately it's had me in its clutches quite strongly.

I have this deep sense of not having achieved enough in my life. I've been at the same job since I graduated and I've hated it for a long time. I realised that over the last few years I've just let myself become detached from life, barely moving forward with my career or experiencing new things. When I was younger I used to have a lot of social anxiety and also BDD-type feelings (never officially diagnosed but I mentioned it to anxiety university counseller once and she agreed I probably had it) which led me to avoid people and social situations even though I desperately wanted to join them. Nowadays, I do still have to fight with those feelings, but I'm pretty comfortable around people.

Unfortunately it almost feels like I overcame one hurdle (social anxiety and BDD) and am now faced with another hurdle of generalised anxiety.

Its very difficult for me to relax if I feel like I have not achieved something that day. I'm lucky as I find my job quite easy, pay is quite good and the commute is short, so this allows me a lot of free time. I deliberately chose a job like that because I felt I wasn't strong enough for a more difficult or stressful job. I'm doing well in my job and some people might envy my position but deep down I know I should be doing more. I had opportunities in the past to do more exciting jobs but I turned them down.