How many times in life do we regret not knowing some skill? I can't sing, I can't play a particular game, I can't speak that language, I can't swim, I can't cook - all these are very familiar regrets that we hear around us. Many of them are our own regrets as well. But the point is - whether they are our regrets or excuses? There is a big difference between regret and an excuse. An excuse is something we can't do because we have never given enough effort to do it. But regret is something which despite our best effort we are unable to do. I can't swim is regret if it is because of some physical disability that prevents you from swimming, but if you never tried to learn swimming, and say I can't swim - it's an excuse. Similar is the case with any other excuse or regret that you might be putting forward.
It is not necessary that you should be able to do everything under the sky. If you are not interested in singing, you don't have to learn it. You can simply say, I don't sing - it is neither regret nor an excuse. Because we all have limited time and energy we have to direct towards certain preferences. We can't spread ourselves so thin doing everything. Therefore, it might be your considered choice to not learn many skills, and that's perfectly fine. There you don't have to say - you can't, better you say - you don't.
But then comes the question of identifying your choices, regrets and excuses. If something is decided out of choice, its fine. But if there is confusion between regret and excuse, you better take them up on a piece of paper and assess why you can't do certain things that you would have otherwise liked to do. Why can't you cook if you actually want to do it? Why can't you speak a particular language if you actually want to learn it? Is there any genuine reason which prevents you from acquiring that skill? If so, what are those reasons? Can they be addressed effectively to give you a chance to put down your hands at it? What stops you from doing so? Is it a physical or mental inability? Is it a lack of resources? Is it a lack of time? Is it the availability of guidance? What is the exact reason that prevents you from converting your inability into ability?
If you say you don't have time, reconsider the answer. Can you not give at least one hour a week to that particular skill? One hour a week, consistently for one year, will certainly put you in a better situation next year. There is hardly any skill which cannot be acquired, at least partially, in 52 hours, which you can dedicate easily over the period of a year. If there is a lack of resources, perhaps alternatives are available that you will find much more cost-effective. You can also rethink your priorities in terms of the allocation of your available resources. Lack of guidance can more or less be resolved in today's time of technology where every kind of lesson is available online. Therefore, it becomes your decision whether you would like to learn something by next year or keep giving the same excuse that you have been giving for many years. Remember, you still have many more years to enjoy the newly acquired skill if you decide to learn it from today onwards and convert your excuse into an opportunity.