Something that can really help with this is getting out of the mindset of identifying yourself by your achievements. You talked about stoicism and being in the present, but it sounds like you're very preoccupied and anxious over how others will percieve your potential success/failure.
One of the aspects of experiencing the present moment is cutting away that ego - realising that ego isn't actually part of conscioussness, it's just something you're choosing to cling onto and identify with.
That doesn't mean that you can't pursue goals and achievement - just that you're not tying them to your happiness. To quote Power Of Now by Eckhart Tolle (which you may want to consider reading):
"Does it matter whether we achieve our outer purpose, whether we succeed or fail in the world? // It matters to you as long as you haven't realised your inner purpose. After that, the outer purpose is just a game that you may continue to play simply because you enjoy it. It is also possible to fail completely in your outer purpose and at the same time totally succeed in your inner purpose. Or the other way round, which is actually more common: outer riches and inner poverty, or to 'gain the world and lose your soul'. Ultimately, of course, every outer purpose is doomed to 'fail' sooner or later, simply because it is subject to the law of impermanence of all things. The sooner you realise that your outer purpose cannot give you lasting fulfillment, the better. When you have seen the limitations of your outer purpose, you give up your unrealistic expectation that it should make you happy, and you make it subservient to your inner purpose."
One of the aspects of experiencing the present moment is cutting away that ego - realising that ego isn't actually part of conscioussness, it's just something you're choosing to cling onto and identify with.
That doesn't mean that you can't pursue goals and achievement - just that you're not tying them to your happiness. To quote Power Of Now by Eckhart Tolle (which you may want to consider reading):
"Does it matter whether we achieve our outer purpose, whether we succeed or fail in the world? // It matters to you as long as you haven't realised your inner purpose. After that, the outer purpose is just a game that you may continue to play simply because you enjoy it. It is also possible to fail completely in your outer purpose and at the same time totally succeed in your inner purpose. Or the other way round, which is actually more common: outer riches and inner poverty, or to 'gain the world and lose your soul'. Ultimately, of course, every outer purpose is doomed to 'fail' sooner or later, simply because it is subject to the law of impermanence of all things. The sooner you realise that your outer purpose cannot give you lasting fulfillment, the better. When you have seen the limitations of your outer purpose, you give up your unrealistic expectation that it should make you happy, and you make it subservient to your inner purpose."