Even if you workout, if you sit like this all day you're setting yourself up for problems.
These problems can include, faulty motor engrams (so your body tends to recruit the wrong muscles during movement), poor circulation, poor breathing, headaches, carpal tunnel/shoulder impingement, a host of back problems, including kyphosis (the hump back seen on some older people)... and the list goes on.
And... to make matters worse, your lifting can be effected, particularly if you do exercises like back rows (e.g. shoulder blades may not move properly so you don't get a good contraction) or back squats (e.g. rounded shoulders can cause bar to rest improperly on the neck instead of the shoulders and rounded back increases injury risk.)
Stop sitting like this!
Then, stretch. In general, focus on the back/sides of the neck, the chest/front of shoulders, the mid (thoracic) back, hips and possibly the ankles (medial, aka inside part) and the wrists.
Also, do MFR (with foam roller, Stick, tennis ball) and/or regular massage therapy can address adhesions/restrictions and encourage circulation and better tissue quality. Of course, be sure to connect with your doc before changing what you do and ask a qualified fit pro or physical therapist for help with your unique situation.