How do I deal with anger in a healthy manner?

I’m carrying around a lot of anger and sometimes I project it onto other people, situations, etc. I’m aware of this, but the feeling is so strong that I carry on regardless.
I used to deal with these feelings with negative coping tools, but now I’m seeing a counsellor (for a couple of years now) about this and I don’t feel it’s dissipating. I also go to the gym 5–6 times p/w to discharge these feelings. I feel great after a workout and feel like I’ve got a lot out of my system, but before long, the anger is back.
I guess I’m angry about a lot of things that have happened in my past, but I’m quite proactive and I’m getting on with my life. I have a great quality of life, love what I do, etc but this feels like a chain around my neck lately. I don’t know what else I can do to get rid of the anger. It feels so toxic.
Does anyone have experience of overcoming these feelings?