Actually I think I'd be quite unhappy without Se. Se is very important to me - at least the manner in which I choose to utilize it. (Although it goes without saying that I don't use it to the extent that an SP would.)
I'm maybe a weird INFJ, but I feel Se has always been an important element of my life. Growing up, my sensory elements were music (playing music) and dance. I've also been very much into nature, my entire life..and perhaps that's where my Se comes out the most and I'd be emotionally dead without it. So out in nature, I am highly attuned to the details around me. It's come in baby steps, I suppose -- as a child I was mostly just focusing on birds, and maybe 8 years ago I started adding flowers into the mix, and of late it's pretty much everything - lichens, animals, insects, details in tree bark...the sky's the limit.
For me, embracing the moment (via hiking, photography, rock-climbing, etc) and the sensory world around me - in an active way at minimum once a week - is necessary to maintain my sense of balance and peace.
Staying active - however you choose to do it - would be a way to exercise Se. Any sort of exercise, or walking outside and soaking in the details around you. *Noting* what's around you - making the effort to pay attention, rather than falling into introverted-contemplation-land. Obviously it would help (would probably even be necessary?) an INFJ to actually like/care about what they're paying attention to, so if you can target something tangible, that you really like, that would be a start. (i.e. I note details in nature because I am passionate about the natural world. However, if you send me down a city street, unless I'm making it a point to look around and pay attention, I won't remember much of anything at all - because I don't care and don't find the details important)
Traveling. Going somewhere new. That feeds my soul too.
