I think you're already in a pretty good place - the fact you have healthy relationships, a good job and you regularly exercise is very very important. And yet,

I think you're already in a pretty good place - the fact you have healthy relationships, a good job and you regularly exercise is very very important. And yet, something is still off by your account. Fatigue, agitation, loneliness. It's not entirely clear to me why you get these fits of agitation, loneliness etc. A lot of depressed people feel down about themselves - they feel like they're worthless, no good, a failure etc. You don't see yourself that way - which is good, but it also calls for more exploration into your predicament. The fact you're kinda already doing everything right (sports, relationships etc) is a sign you may do need external help as you yourself said. An obvious thing that may be lacking by your account is a signifcant other, but in itself is not gonna be a cure for depression.