If you want to succeed by Allah you need to add two things (niyyah and ikhlaas) to any deed you are doing:
An intention to do it for the sake of Allah, not for being a great "scientist", not to be called a good guy, not to be a doctor and being called as a "saver", not for money or reputation or acceptance by people, only for the sake of Allah and maybe in order to strengthen the Ummah by filling a gap where there are only few Muslims!
- "The reward of deeds depends upon the intentions and every person will get the reward according to what he has intended. So whoever emigrated for worldly benefits or for a woman to marry, his emigration was for what he emigrated for."
(See for example in sahih al-Bukhari)
- He who wants to publicise (his deeds), Allah will publicise (his humility), and he who makes a hypocritical display (of his deeds), Allah will make a display of him. (Sahih Muslim)
Do whatever you do sincerely this means with all your might and in the best possible way, don't cheat nor dupe.
And they were not commanded except to worship Allah , [being] sincere to Him in religion, inclining to truth, and to establish prayer and to give zakah. And that is the correct religion (98:6)
Also have in mind ahadith such as:
- ‘Deeds are like vessels. If the lower part is good then the upper part will be good, and if the lower part is bad then the upper part will be bad.’ (Sunan ibn Majah)
- ... Verily, the (results of) deeds done, depend upon the last actions. (Sahih al-Bukhari)
- A bedouin asked the Prophet, "A man may fight for the sake of booty, and another may fight so that he may be mentioned by the people, and a third may fight to show his position (i.e. bravery); which of these regarded as fighting in Allah's Cause?" The Prophet (ﷺ) said, "He who fights so that Allah's Word (i.e. Islam) should be superior, fights for Allah's Cause." (Sahih al-Bukhari)
- Verily Allah does not look to your faces and your wealth but He looks to your heart and to your deeds. (Sahih Muslim)
- ... and this long ahdith in sahih al-Bukhari.
Else if you didn't have a good or correct intention and were not sincer enough in your work or deed, the verse from surat al-Furqan will apply on your deeds:
And We will regard what they have done of deeds and make them as dust dispersed. (25:23)
See also this fatwa islamqa #240287 (in Arabic) on ikhlass
Your mum's advice
Therefore your mum has made some correct statements and missed a few, but on the whole her advice is a useful guideline.
"Everybody will find easy to do such deeds as will lead him to his destined place for which he has been created.' (Sahih al-Bukhari)
So maybe you will never be a great physician or mathematician nor a doctor, but could be good at a mechanical art the most important however is your intention and sincerity.
Allah indeed recommended and one may say ordered seeking knoweldge by many verses, but this order was not general so maybe the best evidence for the recommendation is:
... and say, "My Lord, increase me in knowledge." (20:114)
so learning the whole life is recommended and asking Allah for help on that is even ordered (at least to some extent)!
The rank of people of knowledge is often emphasized in the quran like in:
... Say, "Are those who know equal to those who do not know?" Only they will remember [who are] people of understanding. (39:9)
And it is also in the ahadith there's a a focus on seeking knowledge and on the importance and high rank of scholars and people of knowledge (see for example sahih Muslim, Jami' at-Tirmdihi and sunan ibn Majah).
(See also: What did Prophet Muhammad mean by “Seek knowledge even as far as China"?)
Note that seeking knowledge (which Muslims don't have) is considered as fard kifaya (Also see: Can someone give me examples of fard kifaya?)