I have the exact same problem muscleman. I work/study, I lift, and then I don't know what to do with myself for "fun". Video games have lost their appel for me, and most of TV is crap (not that I would to spend my life sitting in front of a TV, even if it wasn't), this leaves me frustrated- what should I do with my free time? I've spent so much of my time with these past two "hobbies" that I don't really have any other ones, and I'm not sure how to go about finding new ones. Yet, even with the desire to find new "fun" hobbies, I also want to continue to improve myself. What are we to do?
I think before we can decide a course of action, we need to look at why we do the things we do. For the purpose of this conversation, let's say there is two types of activites. Those that we do because they're intrinsically joyful/pleasurable (lets call these column A activities) and those that we do because they'll bring us future joy/pleasure (these will be column B).
Most people, if they even think in terms of these ideas, think that these are two seperate, distinct ideas-completely unrelated. You have started to see the truth however, that you can't simply compartmentalize your activites with no trade off; that life is a zero-sum game, you can't add time to column A without taking away time from column B. Unfortunately, even knowing this we're both faced with a dilemma; we've spent so much time in column A activities (TV, video games) that we no longer enjoy, that we don't know what other column A activities we enjoy, let alone what column B activities to persue. In other words, we don't know ourselves, we don't know who we are.
The cure to this problem, I think, is expirementation. It's time to get up off the couch, out of the house, and try new things until you find the ones you love.
*poof*
A booming voice from above the clouds, a font of wisdom and insight past, reveals himself; apparently he was listening to the entire conversation.
"Mortal, you have answered one enigma only to leave another. The youth wishes to live a full life so that he will not be wracked with regret in the twilight of his life; you have told him to keep trying until he finds the things he loves- but is this not the exact problem that lead him to his current predicament? Will he not be merely filling his life with other "column A" activities that are a mere substitute for his earlier ones? Will he be not be replacing his past poison with but a different one? Is it his fate to be filled with regret in the future, even if he follows this advise?"
Oh wise one, I think not. For whereas before he was denying his soul for mindless activities, he is now searching for it. He is deciding who he wants to be. His goal is not merely to find a somewhat pleasurable activity to pass the time with, but rather to find one in which every minute he spends in pleasure is also a minute that he "improves" himself with.
Think of the painter, or the muscian; are they spending their time "improving themselves" or are they just getting better at doing what they love by doing it? This, I think, is the key to avoiding regret in old age, finding what you love and doing it. For if your life is filled with happiness, what do you truely have to regret?
"Ah, but what of the activities that are not intrinsically pleasureable?"
It's true, not every goal we have is going to be easy to meet, but having a goal and meeting it is what gives our lives meaning, it's what defines us; and every step, and small success, along the way will take you that much closer to where you want to be. Thus the importance of knowing oneself, and knowing where you want to take your life; for if you don't know where you're going then you don't know what steps to take.
In other words, don't look at "self improvement" as an end in and of itself, but rather set goals, and work towards them. By working towards your goals you'll be "self improving" as a consequence of achieving your desires.
Examples:
Goal: I want to have a great body
Work: Bust your balls in the Gym
Self-improvement: Every time you do it, your body gets that much better
Goal: I want to be rich
Work: Studying business and finance, taking risks with money
Self-improvement: With every book you read, and dollar you earn, you understand that much more and are more likely to achieve your goal. What's more if you lose your money, you're much more likely to be able to earn it back.
Sometimes getting what you want requires some blood, swear and tears from you now. That's the price you have to pay. If, on the other hand, you set a goal, and you find out that it's not blood, sweat, and tears, but rather you found the process intrinsically enjoyable- well then make that your "hobby"- that's the ideal really; to love what you're doing while you're doing it, and achieving a long term goal/s at the same time.
If this dosen't happen, just continue working for your goals, they're your self improvement; have your "hobby" be something that you enjoy for blowing off steam, the two don't necessarily have to be the same thing. There are I think, two primary sources of regret in most people when they get old.
The first is that that they set no goals, and then only live for immediate pleasure (like video games/TV, etc). In their old age, they realize they've accomplished nothing.
The second is that their goals are not in line with who they are. They force themselves to be something that they're not, and all their blood, sweat, and tears was for naught. In their old age, they realize they've achieved nothing they care about.
Ultimately, the two are the same thing- denial of the soul. So I say to you muscleman- find out who are you, and then use that to decide who you want to be, set goals in line with that, and then do it. That is the only way to avoid the regret you speak of.