Any tips on how to learn to push yourself?

Great question.

I read it a bit more as, "how hard can I go without blowing up," rather than how one can learn to dwell longer or deeper in the pain cave (so, how to approach a maximum suffer, not push the max higher)

I think it can sometimes be quite useful to blow up during a workout.  By that, I mean push harder than you think you can go, but know that you might blow up.  If you don't let yourself ever GET to the point where you bonk/blow up, etc., then you will never know where that point is.

I've found it in some workouts.  Sadly also in some races!  I prefer to know about where it is (the limit) and try to JUST exceed it in a race (and keep pushing up the max - but that's a different set of activities, I think).  If I'm not ready to fall over and/or puke at the end of a race, I've done it wrong...

So, get out there and TRY to blow yourself up once or twice!  

Works for me.

Hope that helps.  YMMV

Are you talking about pushing Far or Fast?

For fast or hard effort, I would start by pushing in some shorter running races and begin to learn what it feels like to "race" at the edge.  Enter a local 5k and start out just faster than your PR pace and see how long you can hold on.  Apply this feeling to bike and swin as RPE training.  It will take time, so be ready for patience.

Also, do LT testing to learn where that edge is. 

Like most things - Experience.  

Unfortunately, experience is that thing you get right after you needed it 

The best way to learn your limits is to try to exceed them every so often.  Don't be afraid of going too hard and not being able to finish a workout. If you can't finish... ok, bummer, but you just learned something about yourself. 

From experience. Try to beat a previous best on some hard workout. Like the 20 min test on the bike, for one example. Try to do better than what you've done before. Don't worry if you have to granny gear it home (if you did this outside). The goal is to learn about yourself. Even if you end up a little short of making it to the end at that effort, you're still going to get a good workout. Stop & rest a few minutes after if you have to. Then take it easy getting back. This part doesn't really matter, so leave it all in the hard effort.

Also, plan no more than easy workouts the next couple days so that you aren't thinking about missing anything there either.

Sorry, but can you help me on this lol

Isn't that from Sufferfest - I will bust my a$$ today to kick yours tomorrow!!  Or something like that.

The others have said it well: you have to go over the ledge to learn where it is. Once you know what the edge feels like, you practice working out at the edge during training. During a race, you straddle the edge and jump off at the end, but make sure you finish before hitting the ground. 

Just get out and go faster and longer than you think you can just to see if you can do it. You'll be surprised at what you can do. Just know that even though you're tired and it hurts doesn't mean that's as far as you can go. 

I like to think "A normal person would turn around and walk now. They are watching TV at home right now. I am running/riding/swimming. I will beat that person in the race." Or something like that...

2 things that helped me.

1: at the gym sign up for something you know will be difficult (like running on the treadmill for 45min then walk across the room into the 'phyco-cycle' spin class for 45min.... (my legs wobbled so badly and I almost puked in the parking lot after that, but it felt good!))

2: I asked a friend of mine who runs half marathon to help train with me during my long run days. I couldn't go more then a mile without wimping out.... I just got home from a 4mi run at 12.5min mile pace. Slow and steady, but getting there !

Start before the workout. 

As you're getting ready for your run, ride, or swim, are you thinking "I hope I don't run out of gas." or are you thinking "I'm going to finish this no matter what."  ?

Change your focus to the latter (it's a positive expression) and start to visualize the finish, the last mile and how you've accomplished something amazing (and this is true even if you're finishing a short 3-mile run in the peak weak of a marathon plan).  It doesn't matter if you ran 20 miles 3 days before, you got out the door and ran 3 miles today! 

The other thing that helps is to set some bold goals and then make a plan to accomplish them.  You're doing IMCdA next year (I think I saw that).  Whether you realize it yet or not, you CAN complete the swim in 1:30 or 1:45 if it is important enough to you.  It might mean taking swim lessons and swimming with the Master's group every morning for 6 months with the focus and goal of getting good enough at swimming to achieve that goal (not just showing up and puttering around).  Doing so might cut into your time and energy for biking and running.  Is it the right strategy?  Hard to say...it's your life and your goals...so you have to figure out what is right for you. 

Edited to say, this works in all areas of your life, not just triathlon.  What are your goals for work and retirement?  The key is to be specific and to be positive. 

I think it is different for each discipline.

For cycling, I push myself by turning harder gears and by getting in on group rides. The group will make me ride harder than I normally want to on my own.

For running, I can go to any one of several track work outs run by members of the local running club for speed work and work on negative splits.

I also work to keep mileage up and think about my form when I run. This allows me to push harder and build speed.  Most of my 6 runs are 8ish pace during the week but one run a week is 6:40ish or lower pace for 5 miles to push myself hard.  I just make myself go as fast as I can sustain although uncomfortable--I think the mileage I put in makes this possible.

For swimming I work on short sprints. I suck at swimming so this is not an area I am good at pushing at!  

Buy a good heart rate monitor and learn how to use it.

Yep, here is a link to it.

http://www.thesufferfest.com/uncategorized/iwbmattkyt/